Apparatus and method for measuring weight of an occupying item of a seat

ABSTRACT

Arrangement and method for determining weight of an occupying item in a seat including one or more weight sensors arranged to obtain a measurement of the force applied to the seat, a forcing function determination arrangement for measuring a forcing function of the seat and a processor coupled to the weight sensor(s) and forcing function determination arrangement for receiving the measurement of the force applied to the weight sensor(s) and the measurement of the forcing function from the forcing function measurement system and determining the weight of the occupying item based thereon. The forcing function determination arrangement may include an accelerometer and measures effects on the seat caused by load of a seatbelt associated with the seat and/or effects on the seat of road roughness, steering maneuvers, and a vehicle suspension system.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of:

[0002] 1) U.S. patent application Ser. No. 09/500,346 filed Feb. 8, 2000which in turn is a continuation-in-part of U.S. patent application Ser.No. 09/128,490, now U.S. Pat. No. 6,078,854, which in turn is acontinuation-in-part of both U.S. patent application Ser. No. 08/474,783filed Jun. 7, 1995, now U.S. Pat. No. 5,822,707, and U.S. patentapplication Ser. No. 08/970,822 filed Nov. 14, 1997, now U.S. Pat. No.6,081,757;

[0003] 2) U.S. patent application Ser. No. 09/849,558 filed May 4, 2001which in turn is a continuation-in-part of U.S. patent application Ser.No.09/193,209 filed Nov. 17, 1998, now U.S. Pat. No. 6,242,701, which inturn is a continuation-in-part of U.S. patent application Ser. No.09/128,490 filed Aug. 4, 1998, now U.S. Pat. No. 6,078,854, which inturn is a continuation-in-part of both U.S. patent application Ser. No.08/474,783 filed Jun. 7, 1995, now U.S. Pat. No. 5,822,707, and U.S.patent application Ser. No.08/970,822 filed Nov. 14, 1997, now U.S. Pat.No. 6,081,757;

[0004] 3) U.S. patent application Ser. No. 09/849,559 filed May 4, 2001which in turn is a continuation-in-part of U.S. patent application Ser.No. 09/193,209 filed Nov. 17, 1998, now U.S. Pat. No. 6,242,701, whichin turn is a continuation-in-part of U.S. patent application Ser. No.09/128,490 filed Aug. 4, 1998, now U.S. Pat. No. 6,078,854, which inturn is a continuation-in-part of both U.S. patent application Ser. No.08/474,783 filed Jun. 7, 1995, now U.S. Pat. No. 5,822,707, and U.S.patent application Ser. No.08/970,822 filed Nov. 14, 1997, now U.S. Pat.No. 6,081,757;

[0005] 4) U.S. patent application Ser. No. 09/901,879 filed Jul. 9, 2001which in turn is a continuation of U.S. patent application Ser. No.09/849,559 filed May 4, 2001 which in turn is a continuation-in-part ofU.S. patent application Ser. No.09/193,209 filed Nov. 17, 1998, now U.S.Pat. No. 6,242,701, which in turn is a continuation-in-part of U.S.patent application Ser. No. 09/128,490 filed Aug. 4, 1998, now U.S. Pat.No. 6,078,854, which in turn is a continuation-in-part of both U.S.patent application Ser. No. 08/474,783 filed Jun. 7, 1995, now U.S. Pat.No. 5,822,707, and U.S. patent application Ser. No. 08/970,822 filedNov. 14, 1997, now U.S. Pat. No. 6,081,757;

[0006] 5) U.S. patent application Ser. No.09/753,186 filed Jan. 2, 2001;

[0007] 6) U.S. patent application Ser. No. 09/767,020 filed Jan. 23,2001; and

[0008] 7) U.S. patent application Ser. No. 09/770,974 filed Jan. 26,2001.

FIELD OF THE INVENTION

[0009] The present invention relates to methods and apparatus formeasuring the weight of an occupying item of a seat, in particular, aseat in an automotive vehicle.

[0010] The present invention also relates to apparatus and methods foradjusting a vehicle component, system or subsystem in which theoccupancy of a seat, also referred to as the “seated state” herein, isevaluated using at least a weight measuring apparatus and the component,system or subsystem may then be adjusted based on the evaluatedoccupancy thereof. The vehicle component, system or subsystem,hereinafter referred to simply as a component, may be any adjustablecomponent of the vehicle including, but not limited to, the bottomportion and backrest of the seat, the rear view and side mirrors, thebrake, clutch and accelerator pedals, the steering wheel, the steeringcolumn, a seat armrest, a cup holder, the mounting unit for a cellulartelephone or another communications or computing device and the visors.Further, the component may be a system such an as airbag system, thedeployment or suppression of which is controlled based on theseated-state of the seat. The component may also be an adjustableportion of a system the operation of which might be advantageouslyadjusted based on the seated-state of the seat, such as a device forregulating the inflation or deflation of an airbag that is associatedwith an airbag system.

[0011] The present invention also relates to apparatus and method forautomatically adjusting a vehicle component to a selected or optimumposition for an occupant of a seat based on at least two measuredmorphological characteristics of the occupant, one of which is theweight of the occupant. Other morphological characteristics include theheight of the occupant, the length of the occupant's arms, the length ofthe occupant's legs, the occupant's head diameter, facial features andthe inclination of the occupant's back relative to the seat bottom.Other morphological characteristics are also envisioned for use in theinvention including iris pattern properties from an iris scan, voiceprint and finger and hand prints.

BACKGROUND OF THE INVENTION

[0012] Automobiles equipped with airbags are well known in the priorart. In such airbag systems, the car crash is sensed and the airbagsrapidly inflated thereby insuring the safety of an occupation in a carcrash. Many lives have now been saved by such airbag systems. However,depending on the seated state of an occupant, there are cases where hisor her life cannot be saved even by present airbag systems. For example,when a passenger is seated on the front passenger seat in a positionother than a forward facing, normal state, e.g., when the passenger isout of position and near the deployment door of the airbag, there willbe cases when the occupant will be seriously injured or even killed bythe deployment of the airbag.

[0013] Also, sometimes a child seat is placed on the passenger seat in arear facing position and there are cases where a child sitting in such aseat has been seriously injured or killed by the deployment of theairbag.

[0014] Furthermore, in the case of a vacant seat, there is no need todeploy an airbag, and in such a case, deploying the airbag isundesirable due to a high replacement cost and possible release of toxicgases into the passenger compartment. Nevertheless, most airbag systemswill deploy the airbag in a vehicle crash even if the seat isunoccupied.

[0015] For these reasons, there has been proposed a seated-statedetecting unit such as disclosed in the following U.S. patents, whichare incorporated herein by reference in their entirety to the extent thedisclosure of these patents is necessary, assigned to the currentassignee of the present application: Breed et al. (U.S. Pat. No.5,563,462); Breed et al. (U.S. Pat. No. 5,829,782); Breed et al. (U.S.Pat. No. 5,822,707): Breed et al. (U.S. Pat. No. 5,694,320); Breed etal. (U.S. Pat. No. 5,748,473); and Varga et al. (U.S. Pat. No.5,943,295). Typically, in some of these designs as many as three or foursensors or sets of sensors are installed at three or four points in avehicle passenger compartment for transmitting ultrasonic orelectromagnetic waves toward the passenger or driver's seat andreceiving the reflected waves. Using appropriate hardware and software,the approximate configuration of the occupancy of either the passengeror driver seat can be determined thereby identifying and categorizingthe occupancy of the relevant seat.

[0016] However, in the aforementioned literature using ultrasonics, thepattern of reflected ultrasonic waves from an adult occupant who may beout of position is sometimes similar to the pattern of reflected wavesfrom a rear facing child seat. Also, it is sometimes difficult todiscriminate the wave pattern of a normally seated child with the seatin a rear facing position from an empty seat with the seat in a moreforward position. In other cases, the reflected wave pattern from a thinslouching adult with raised knees can be similar to that from a rearfacing child seat. In still other cases, the reflected pattern from apassenger seat which is in a forward position can be similar to thereflected wave pattern from a seat containing a forward facing childseat or a child sitting on the passenger seat. In each of these cases,the prior art ultrasonic systems can suppress the deployment of anairbag when deployment is desired or, alternately, can enable deploymentwhen deployment is not desired. Similar confusing situations can occuralso for capacitive, electric field and optical occupant sensingsystems.

[0017] If the discrimination between these cases can be improved, thenthe reliability of the seated-state detecting unit can be improved andmore people saved from death or serious injury, In addition, theunnecessary deployment of an airbag can be prevented.

[0018] With respect to the adjustment of a vehicular seat, theadjustment of an automobile seat occupied by a driver of the vehicle isnow accomplished by the use of either electrical switches and motors orby mechanical levers. As a result, the driver's seat is rarely placed atthe proper driving position which is defined as the seat location whichplaces the eyes of the driver in the so-called “eye ellipse” and permitshim or her to comfortably reach the pedals and steering wheel. The “eyeellipse” is the optimum eye position relative to the windshield and rearview mirror of the vehicle.

[0019] The eye ellipse, which is actually an ellipsoid, is rarelyachieved by the actions of the driver for a variety of reasons. Onespecific reason is the poor design of most seat adjustment systemsparticularly the so-called “4-way-seat”. It is known that there arethree degrees of freedom of a seat bottom, namely vertical,longitudinal, and rotation about the lateral or pitch axis. The4-way-seat provides four motions to control the seat: (1) raising orlowering the front of the seat, (2) raising or lowering the back of theseat, (3) raising or lowering the entire seat, (4) moving the seat foreand aft. Such a seat adjustment system causes confusion since there arefour control motions for three degrees of freedom. As a result, vehicleoccupants are easily frustrated by such events as when the control toraise the seat is exercised, the seat not only is raised but is alsorotated. Occupants thus find it difficult to place the seat in theoptimum location using this system and frequently give up trying leavingthe seat in an improper driving position

[0020] Many vehicles today are equipped with a lumbar support systemthat is never used by most occupants. One reason is that the lumbarsupport cannot be preset since the shape of the lumbar for differentoccupants differs significantly, i.e., a tall person has significantlydifferent lumbar support requirements than a short person. Withoutknowledge of the size of the occupant, the lumbar support cannot beautomatically adjusted.

[0021] As discussed in the above referenced '320 patent, inapproximately 95% of the cases where an occupant suffers a whiplashinjury, the headrest is not properly located to protect him or her in arear impact collision. Also, the stiffness and damping characteristicsof a seat are fixed and no attempt is made in any production vehicle toadjust the stiffness and damping of the seat in relation to either thesize or weight of an occupant, or to the environmental conditions suchas road roughness. All of these adjustments, if they are to be doneautomatically, require knowledge of the morphology of the seat occupant.

[0022] Systems are now being used to attempt to identify the vehicleoccupant based on a coded key or other object carried by the occupant.This requires special sensors within the vehicle to recognize the codedobject. Also, the system only works if the coded object is used by theparticular person for whom the vehicle was programmed. If the vehicle isused by a son or daughter, for example, who use their mother's key thenthe wrong seat adjustments are made. Also, these systems preserve thechoice of seat position without any regard for the correctness of theseat position. With the problems associated with the 4-way seats, it isunlikely that the occupant ever properly adjusts the seat. Therefore,the error will be repeated every time the occupant uses the vehicle.

[0023] Moreover, these coded systems are a crude attempt to identify theoccupant. An improvement can be made if the morphologicalcharacteristics of the occupant can be measured as described below. Suchmeasurements can be made of the height and weight, for example, and usednot only to adjust a vehicular component to a proper position but alsoto remember that position, as fine tuned by the occupant, forre-positioning the component the next time the occupant occupies theseat. For the purposes herein, a morphological characteristic will meanany measurable property of a human such as height, weight, leg or armlength, head diameter, facial features, iris patterns, voice, finger orhand prints etc.

[0024] As discussed more fully below, in a preferred implementation,once at least one and preferably two of the morphologicalcharacteristics of a driver are determined, e.g., by measuring his orher height and weight, the component such as the seat can be adjustedand other features or components can be incorporated into the systemincluding, for example, the automatic adjustment of the rear view and/orside mirrors based on seat position and occupant height. In addition, adetermination of an out-of-position occupant can be made and basedthereon, airbag deployment suppressed if the occupant is more likely tobe injured by the airbag than by the accident without the protection ofthe airbag. Furthermore, the characteristics of the airbag including theamount of gas produced by the inflator and the size of the airbag exitorifices can be adjusted to provide better protection for smalllightweight occupants as well as large, heavy people. Even the directionof the airbag deployment can, in some cases, be controlled.

[0025] Still other features or components can now be adjusted based onthe measured occupant morphology as well as the fact that the occupantcan now be identified. Some of these features or components include theadjustment of seat armrest, cup holder, steering wheel (angle andtelescoping), pedals, visors phone location and for that matter theadjustment of all things in the vehicle which a person must reach orinteract with. Some items that depend on personal preferences can alsobe automatically adjusted including the radio station, temperature, rideand others.

[0026] “Pattern recognition” as used herein will generally mean anysystem which processes a signal that is generated by an object (e.g.,representative of a pattern of returned or received impulses, waves orother physical property specific to and/or characteristic of and/orrepresentative of that object) or is modified by interacting with anobject, in order to determine to which one of a set of classes that theobject belongs. Such a system might determine only that the object is oris not a member of one specified class, or it might attempt to assignthe object to one of a larger set of specified classes, or find that itis not a member of any of the classes in the set. The signals processedare generally a series of electrical signals coming from transducersthat are sensitive to acoustic (ultrasonic) or electromagnetic radiation(e.g., visible light, infrared radiation, radar, or any otherfrequency), although other sources of information are frequentlyincluded.

[0027] A trainable or a trained pattern recognition system as usedherein generally means a pattern recognition system which is taught torecognize various patterns constituted within the signals by subjectingthe system to a variety of examples. The most successful such system isthe neural network or modular neural network. Thus, to generate thepattern recognition algorithm, test data is first obtained whichconstitutes a plurality of sets of returned waves, or wave patterns orother data, from an object (or from the space in which the object willbe situated in the passenger compartment, i.e., the space above theseat) and an indication of the identity of that object, (e.g., a numberof different objects are tested to obtain the unique wave patterns fromeach object). As such, the algorithm is generated, and stored in acomputer processor, and which can later be applied to provide theidentity of an object based on the wave or other pattern being receivedduring use by a receiver connected to the processor and otherinformation. For the purposes here, the identity of an object sometimesapplies to not only the object itself but also to its location and/ororientation in the passenger compartment. For example, a rear facingchild seat is a different object than a forward facing child seat and anout-of-position adult is a different object than a normally seatedadult.

[0028] Other means of pattern recognition exist where the training isdone by the researcher including Fuzzy Logic and Sensor Fusion systems.

[0029] To “identify” as used herein will generally mean to determinethat the object belongs to a particular set or class. The class may beone containing, for example, all rear facing child seats, one containingall human occupants, or all human occupants not sitting in a rear facingchild seat depending on the purpose of the system. In the case where aparticular person is to be recognized, the set or class will containonly a single element, i.e., the person to be recognized.

[0030] To “ascertain the identity of” as used herein with reference toan object will generally mean to determine the type or nature of theobject (obtain information as to what the object is), i.e., that theobject is an adult, an occupied rear facing child seat, an occupiedfront facing child seat, an unoccupied rear facing child seat, anunoccupied front facing child seat, a child, a dog, a bag of groceries,etc.

[0031] An “object” or “occupying item” of a seat may be a livingoccupant such as a human or a dog, another living organism such as aplant, or an inanimate object such as a box or bag of groceries or anempty child seat.

[0032] “Out-of-position” as used for an occupant will generally meanthat the occupant, either the driver or a passenger, is sufficientlyclose to the occupant protection apparatus (airbag) prior to deploymentthat he or she is likely to be more seriously injured by the deploymentevent itself than by the accident. It may also mean that the occupant isnot positioned appropriately in order to attain the beneficial,restraining effects of the deployment of the airbag. As for the occupantbeing too close to the airbag, this typically occurs when the occupant'shead or chest is closer than some distance such as about 5 inches fromthe deployment door of the airbag module. The actual distance valuewhere airbag deployment should be suppressed depends on the design ofthe airbag module and is typically farther for the passenger airbag thanfor the driver airbag.

[0033] “Transducer” as used herein will generally mean the combinationof a transmitter and a receiver. In some cases, the same device willserve both as the transmitter and receiver while in others two separatedevices adjacent to each other will be used. In some cases, atransmitter is not used and in such cases transducer will mean only areceiver. Transducers include, for example, capacitive, inductive,ultrasonic, electromagnetic (antenna, CCD, CMOS arrays), weightmeasuring or sensing devices.

[0034] “Adaptation” as used here represents the method by which aparticular occupant sensing system is designed and arranged for aparticular vehicle model. It includes such things as the process bywhich the number, kind and location of various transducers isdetermined. For pattern recognition systems, it includes the process bywhich the pattern recognition system is taught to recognize the desiredpatterns. In this connection, it will usually include (1) the method oftraining, (2) the makeup of the databases used for training, testing andvalidating the particular system, or, in the case of a neural network,the particular network architecture chosen, (3) the process by whichenvironmental influences are incorporated into the system, and (4) anyprocess for determining the pre-processing of the data or the postprocessing of the results of the pattern recognition system. The abovelist is illustrative and not exhaustive. Basically, adaptation includesall of the steps that are undertaken to adapt transducers and othersources of information to a particular vehicle to create the system thataccurately identifies and determines the location of an occupant orother object in a vehicle.

[0035] Heretofore, various methods have been proposed for measuring theweight of an occupying item of a vehicular seat. The methods includepads, sheets or films that have placed in the seat cushion which attemptto measure the pressure distribution of the occupying item. Prior to itsfirst disclosure in U.S. Pat. No. 5,822,707 referenced above, systemsfor measuring occupant weight based on the strain in the seat structurehad not been considered. Prior art weight measurement systems have beennotoriously inaccurate. Thus, a more accurate weight measuring system isdesirable. The strain and bladder weight measurement systems describedherein, substantially eliminate the inaccuracy problems of prior artsystems and permit an accurate determination of the weight of theoccupying item of the vehicle seat. Additionally, as disclosed herein,in many cases, sufficient information can be obtained for the control ofa vehicle component without the necessity of determining the entireweight of the occupant. For example, the force that the occupant exertson one of the three support members may be sufficient.

[0036] A “vehicle” as used herein will generally mean a self-propelledland vehicle such as a car, truck or bus, but can also encompassairplanes, trains (locomotives and non-self-propelled cars), boats andnon-self-propelled and vehicles such as truck trailers.

[0037] Most, if not all, of the problems discussed above are difficultto solve or unsolvable using conventional technology.

OBJECTS OF THE INVENTION

[0038] Accordingly, it is a principal object of the present invention toprovide new and improved apparatus and methods for measuring the weightof an occupying item on a vehicle seat which apparatus and methods maybe integrated into vehicular component adjustment apparatus and methodswhich evaluate the occupancy of the seat and adjust the location and/ororientation relative to the occupant and/or operation of a part of thecomponent or the component in its entirety based on the evaluatedoccupancy of the seat.

[0039] It is another object of the present invention to provide new andimproved vehicular seats including a weight measuring feature and weightmeasuring methods for implementation in connection with vehicular seats.

[0040] It is another object of the present invention to obtain ameasurement of the weight of an occupying item in a seat of a vehiclewhile compensating for effects caused by a seatbelt, road roughness,steering maneuvers and a vehicle suspension system.

[0041] It is yet another object of the present invention to classify anoccupying item in a seat based on dynamic forces measured by a weightsensor associated with the seat, with an optional compensation foreffects caused by the seatbelt, road roughness, etc.

[0042] It is still another object of the present invention to determinewhether an occupying item is belted based on dynamic forces measured bya weight sensor associated with the seat, with an optional compensationfor effects caused by the seatbelt, road roughness, etc.

[0043] It is still another object of the present invention to determinewhether an occupying item in the seat is alive or inanimate based ondynamic forces measured by a weight sensor associated with the seat,with an optional compensation for effects caused by the seatbelt, roadroughness, etc.

[0044] It is yet another object of the invention to determine thelocation of the occupying item on a seat based on dynamic forcesmeasured by a weight sensor associated with the seat, with an optionalcompensation for effects caused by the seatbelt, road roughness, etc.

[0045] Additional objects and advantages of this invention include:

[0046] 1. to provide new and improved vehicular seats in which theweight applied by an occupying item to the seat is measured based oncapacitance between conductive and/or metallic members underlying theseat cushion.

[0047] 2. to provide new and improved adjustment apparatus and methodsthat evaluate the occupancy of the seat and adjust the location and/ororientation relative to the occupant and/or operation of a part of thecomponent or the component in its entirety based on the evaluatedoccupancy of the seat and on a measurement of the occupant's weight or ameasurement of a force exerted by the occupant on the seat.

[0048] 3. to provide new and improved adjustment apparatus and methodsthat evaluate the occupancy of the seat by a combination of ultrasonicsensors and additional sensors and adjust the location and/ororientation relative to the occupant and/or operation of a part of thecomponent or the component in its entirety based on the evaluatedoccupancy of the seat.

[0049] 4. to provide new and improved adjustment apparatus and methodsthat reliably discriminate between a normally seated passenger and aforward facing child seat, between an abnormally seated passenger and arear facing child seat, and whether or not the seat is empty and adjustthe location and/or orientation relative to the occupant and/oroperation of a part of the component or the component in its entiretybased thereon.

[0050] 5. to provide an improved weight measurement system and therebyimprove the accuracy of another apparatus or system which utilizesmeasured weight as input, e.g., a component adjustment apparatus.

[0051] 6. to provide new and improved adjustment apparatus and methodsthat evaluate the occupancy of the seat without the problems mentionedabove.

[0052] 7. to provide a system for passively and automatically adjustingthe position of a vehicle component to a near optimum location based onthe size of an occupant.

[0053] 8. to provide a system for recognizing a particular occupant of avehicle and thereafter adjusting various components of the vehicle inaccordance with the preferences of the recognized occupant.

[0054] 9. to provide systems for approximately locating the eyes of avehicle driver to thereby permit the placement of the driver's eyes at aparticular location in the vehicle.

[0055] 10. to provide a pattern recognition system to permit moreaccurate location of an occupant's head and the parts thereof and to usethis information to adjust a vehicle component.

[0056] 11. to provide a method of determining whether a seat is occupiedand, if not, leaving the seat at a neutral position.

[0057] 12. to provide a system for automatically adjusting the positionof various components of the vehicle to permit safer and more effectiveoperation of the vehicle including the location of the pedals andsteering wheel.

[0058] 13. to determine whether an occupant is out-of-position relativeto the airbag and if so, to suppress deployment of the airbag in asituation in which the airbag would otherwise be deployed.

[0059] 14. to adjust the flow of gas into and/or out of the airbag basedon the morphology and position of the occupant to improve theperformance of the airbag in reducing occupant injury.

[0060] 15. to provide a system where the morphological characteristicsof an occupant are measured by sensors located within the seat.

[0061] 16. to provide a system and method wherein the weight of anoccupant is determined utilizing sensors located on the seat structure.

[0062] 17. to provide a system and method wherein other morphologicalproperties are used to identify an individual including facial features,iris patterns, voiceprints, fingerprints and handprints.

[0063] Further objects of the present invention will become apparentfrom the following discussion of the preferred embodiments of theinvention.

SUMMARY OF THE INVENTION

[0064] Accordingly, to achieve at least one of the above objects, anarrangement for determining weight of an occupying item in a seatcomprises at least one weight sensor arranged to obtain a measurement ofthe force applied to the seat, a forcing function determinationarrangement for measuring a forcing function of the seat and a processorcoupled to the weight sensor(s) and forcing function determinationarrangement for receiving the measurement of the force applied to theweight sensor(s) and the measurement of the forcing function from theforcing function measurement system and determining the weight of theoccupying item based thereon.

[0065] The forcing function determination arrangement may comprise atleast one accelerometer, for example, a vertical accelerometer. Theforcing function determination arrangement may be arranged to measureeffects on the seat caused by load of a seatbelt associated with theseat whereby the forcing function is dependent on the load caused by theseatbelt. Also, the forcing function determination arrangement canmeasure effects on the seat of road roughness, steering maneuvers, and avehicle suspension system whereby the forcing function is dependent onthe road roughness, steering maneuvers and the vehicle suspensionsystem.

[0066] The weight sensors may be of various, different types including abladder having at least one chamber and at least one transducer formeasuring the pressure in a respective chamber.

[0067] The processor can be designed or programmed to determine whetherthe occupying item is belted by analyzing the measurements from by theweight sensor(s) over time and the forcing function of the seat from theforcing function determination arrangement over time. Also, theprocessor can be designed or programmed to differentiate between animateand inanimate objects by analyzing measurements from the weightsensor(s) over time and the forcing function of the seat from theforcing function determination arrangement over time. In addition, theprocessor can be designed or programmed to determine the position of theoccupying item on the seat by analyzing the measurements from the weightsensor(s) over time and the forcing function of the seat from theforcing function determination arrangement over time

[0068] Another arrangement for determining weight of an occupying itemin a seat comprises at least one weight sensor arranged to obtain ameasurement of the force applied to the seat by the occupying item, ameasuring system for measuring dynamic forces being applied to the seatand a processor coupled to the weight sensor(s) and measuring system forreceiving the measurement of the force applied to the seat from theweight sensor(s) and the dynamic forces from the measuring system anddetermining the weight of the occupying item based thereon.

[0069] The measuring system may comprise at least one accelerometer, forexample, a vertical accelerometer. It also may be arranged to measureeffects on the seat caused by load of a seatbelt associated with theseat and/or effects on the seat of road roughness, steering maneuvers,and a vehicle suspension system.

[0070] The weight sensors may be of various, different types including abladder having at least one chamber and at least one transducer formeasuring the pressure in a respective chamber.

[0071] The processor can be designed or programmed to determine whetherthe occupying item is belted by analyzing the measurements from by theweight sensor(s) over time and the dynamic forces applied to the seat bythe measuring system over time. Also, the processor can be designed orprogrammed to differentiate between animate and inanimate objects byanalyzing measurements from the weight sensor(s) over time and thedynamic forces applied to the seat by the measuring system over time. Inaddition, the processor can be designed or programmed to determine theposition of the occupying item on the seat by analyzing the measurementsfrom the weight sensor(s) over time and the dynamic forces applied tothe seat by the measuring system over time

[0072] An arrangement for classifying an occupying item in a seat inaccordance with the invention comprises at least one weight sensorarranged to measure the force applied to the seat at time intervals anda processor coupled to the weight sensor(s) for receiving the forcemeasurements therefrom. The processor analyzes the force measurementsfrom the weight sensor(s) over time to discern patterns providingclassification information about the occupying item. More particularly,the processor may be trained to discern patterns providing informationabout the occupying item by conducting tests in which differentoccupying items are placed in the seat and measurements of the forceapplied to the seat are obtained by the weight sensor(s), before, duringand after placement of the occupying item in the seat.

[0073] A forcing function determination arrangement may be provided andcoupled to the processor for measuring a forcing function of the seat.The processor then considers the forcing function in the discerning ofthe patterns providing classification information about the occupyingitem.

[0074] A measuring system can also be coupled to the processor formeasuring dynamic forces applied to the seat. The processor would thenconsider the dynamic forces applied to the seat in the discerning of thepatterns providing classification information about the occupying item.

[0075] To achieve one or more objects of the invention, a method fordetermining weight of an occupying item in a seat of a vehicle comprisesthe steps of measuring the force applied to the seat, measuring aforcing function of the seat, and determining the weight of theoccupying item based on the measured force applied to the seat and themeasured forcing function. The features of the arrangements describedabove can be used in connection with this method.

[0076] Another method for determining weight of an occupying item in aseat comprises the steps of measuring the force applied to the seat,measuring dynamic forces applied to the seat and determining the weightof the occupying item based on the measured force applied to the seatand the measured dynamic forces applied to the seat. The features of thearrangements described above can be used in connection with this method.

[0077] A method for classifying an occupying item in a seat inaccordance with the invention comprises the steps of measuring the forceapplied to the seat at time intervals and identifying patternsindicative of a classification of particular occupying items based onthe measurements of the force applied to the seat over time.Identification of such patterns may entail utilizing a patternrecognition algorithm to identify patterns from the measurements of theforce applied to the seat over time. For example, the patternrecognition algorithm can be trained by conducting tests in whichdifferent occupying items are placed in the seat and measuring the forceapplied to the seat before, during and after placement of the occupyingitem in the seat. Further, a forcing function of the seat can bemeasured so that identification of patterns would additionally entailidentifying patterns based on the measurements of the force applied tothe seat and the forcing function. Also, dynamic forces applied to theseat may be measured so that identification of patterns might entailidentifying patterns based on the measurements of the force applied tothe seat and the measurements of the dynamic forces applied to the seat.

BRIEF DESCRIPTION OF THE DRAWINGS

[0078] The following drawings are illustrative of embodiments of theinvention and are not meant to limit the scope of the invention asencompassed by the claims.

[0079]FIG. 1 shows a seated-state detecting unit in accordance with thepresent invention and the connections between ultrasonic orelectromagnetic sensors, a weight sensor, a reclining angle detectingsensor, a seat track position detecting sensor, a heartbeat sensor, amotion sensor, a neural network circuit, and an airbag system installedwithin a vehicle compartment;

[0080]FIG. 2 is a perspective view of a vehicle showing the position ofthe ultrasonic or electromagnetic sensors relative to the driver andfront passenger seats.;

[0081]FIG. 3 is a circuit diagram of the seated-state detecting unit ofthe present invention;

[0082] FIGS. 4(a), 4(b) and 4(c) are each a diagram showing theconfiguration of the reflected waves of an ultrasonic wave transmittedfrom each transmitter of the ultrasonic sensors toward the passengerseat, obtained within the time that the reflected wave arrives at areceiver, FIG. 4(a) showing an example of the reflected waves obtainedwhen a passenger is in a normal seated-state, FIG. 4(b) showing anexample of the reflected waves obtained when a passenger is in anabnormal seated-state (where the passenger is seated too close to theinstrument panel), and FIG. 4(c) showing a transmit pulse;

[0083]FIG. 5 is a diagram of the data processing of the reflected wavesfrom the ultrasonic or electromagnetic sensors;

[0084]FIG. 6 is a flowchart showing the training steps of a neuralnetwork circuit;

[0085]FIG. 7(a) is an explanatory diagram of a process for normalizingthe reflected wave and shows normalized reflected waves; and

[0086]FIG. 7(b) is a diagram similar to FIG. 7(a) showing a step ofextracting data based on the normalized reflected waves and a step ofweighting the extracted data by employing the data of the seat trackposition detecting sensor, the data of the reclining angle detectingsensor, and the data of the weight sensor.

[0087]FIG. 8 is a perspective view of an automatic seat adjustmentsystem, with the seat shown in phantom, with a movable headrest andsensors for measuring the height of the occupant from the vehicle seatshowing motors for moving the seat and a control circuit connected tothe sensors and motors.

[0088]FIG. 9 is a perspective view of the seat shown in FIG. 8 with theaddition of a weight sensor shown mounted onto the seat.

[0089]FIG. 9A is a view taken along line 9A-9A in FIG. 9.

[0090]FIG. 9B is an enlarged view of the section designated 9B in FIG.9A.

[0091]FIG. 9C is a view of another embodiment of a seat with a weightsensor similar to the view shown in FIG. 9A.

[0092]FIG. 9D is a view of another embodiment of a seat with a weightsensor in which a SAW strain gage is placed on the bottom surface of thecushion.

[0093]FIG. 10 is a side plan view of the interior of an automobile, withportions cut away and removed, with two occupant height measuringsensors, one mounted into the headliner above the occupant's head andthe other mounted onto the A-pillar and also showing a seatbeltassociated with the seat wherein the seatbelt has an adjustable upperanchorage point which is automatically adjusted based on the height ofthe occupant.

[0094]FIG. 11 is a view of the seat of FIG. 8 showing motors forchanging the tilt of seat back and the lumbar support.

[0095]FIG. 12 is a view of the seat of FIG. 8 showing a system forchanging the stiffness and the damping of the seat.

[0096]FIG. 12A is a view of the seat of FIG. 8 wherein the bladdercontains a plurality of chambers.

[0097]FIG. 13 is a view as in FIG. 10 showing a driver and driver seatwith an automatically adjustable steering column and pedal system whichis adjusted based on the morphology of the driver.

[0098]FIG. 14 is a perspective view of the interior of the passengercompartment of an automobile, with parts cut away and removed, showing avariety of transmitters that can be used in a phased array system.

[0099]FIG. 15 is a view similar to FIG. 8 showing the occupant's eyesand the seat adjusted to place the eyes at a particular verticalposition for proper viewing through the windshield and rear view mirror.

[0100]FIG. 16 is a view similar to FIG. 8 showing an inflated airbag andan arrangement for controlling both the flow of gas into and the flow ofgas out of the airbag during the crash where the determination is madebased on a height sensor located in the headrest and a weight sensor inthe seat.

[0101]FIG. 17A is a schematic drawing of the basic embodiment of theadjustment system in accordance with the invention.

[0102]FIG. 17B is a schematic drawing of another basic embodiment of theadjustment system in accordance with the invention.

[0103]FIG. 18 is a perspective view of a one embodiment of an apparatusfor measuring the weight of an occupying item of a seat illustratingweight sensing transducers mounted on a seat control mechanism portionwhich is attached directly to the seat.

[0104]FIG. 19 illustrates a seat structure with the seat cushion andback cushion removed illustrating a three-slide attachment of the seatto the vehicle and preferred mounting locations on the seat structurefor strain measuring weight sensors of an apparatus for measuring theweight of an occupying item of a seat in accordance with the invention.

[0105]FIG. 19A illustrates an alternate view of the seat structuretransducer mounting location taken in the circle A of FIG. 19 with theaddition of a gusset and where the strain gage is mounted onto thegusset.

[0106]FIG. 19B illustrates a mounting location for a weight sensingtransducer on a centralized transverse support member in an apparatusfor measuring the weight of an occupying item of a seat in accordancewith the invention.

[0107]FIGS. 20A, 20B and 20C illustrate three alternate methods ofmounting strain transducers of an apparatus for measuring the weight ofan occupying item of a seat in accordance with the invention onto atubular seat support structural member.

[0108]FIG. 21 illustrates an alternate weight sensing transducerutilizing pressure sensitive transducers.

[0109]FIG. 21A illustrates a part of another alternate weight sensingsystem for a seat.

[0110]FIG. 22 illustrates an alternate seat structure assembly utilizingstrain transducers.

[0111]FIG. 22A is a perspective view of a cantilevered beam type loadcell for use with the weight measurement system of this invention formounting locations of FIG. 22, for example.

[0112]FIG. 22B is a perspective view of a simply supported beam typeload cell for use with the weight measurement system of this inventionas an alternate to the cantilevered load cell of FIG. 22A.

[0113]FIG. 22C is an enlarged view of the portion designated 22C in FIG.22B.

[0114]FIG. 22D is a perspective view of a tubular load cell for use withthe weight measurement system of this invention as an alternate to thecantilevered load cell of FIG. 22A.

[0115]FIG. 22E is a perspective view of a torsional beam load cell foruse with the weight measurement apparatus in accordance with theinvention as an alternate to the cantilevered load cell of FIG. 22A.

[0116]FIG. 23 is a schematic of a vehicle with several accelerometersand/or gyroscopes at preferred locations in the vehicle.

[0117]FIG. 24 is a schematic showing the manner in which dynamic forcesof the vehicle can be compensated for in a weight measurement of theoccupant.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0118] Referring to the accompanying drawings wherein like referencenumbers designate the same or similar elements, FIG. 1 shows a passengerseat 1 to which an adjustment apparatus including a seated-statedetecting unit according to the present invention may be applied. Theseat 1 includes a horizontally situated bottom seat portion 2 and avertically oriented back portion 3. The seat portion 2 is provided withone or more weight sensors 6 and 7 that determine the weight of theobject occupying the seat. The coupled portion between the seatedportion 2 and the back portion 3 is provided with a reclining angledetecting sensor 9, which detects the tilted angle of the back portion 3relative to the seat portion 2. The seat portion 2 is provided with aseat track position-detecting sensor 10. The seat track positiondetecting sensor 10 fulfills a role of detecting the quantity ofmovement of the seat 1 which is moved from a back reference position,indicated by the dotted chain line. Embedded within the seatback is aheartbeat sensor 31 and a motion sensor 33. Attached to the headliner isa capacitance sensor 32. The seat 1 may be the driver seat, the frontpassenger seat or any other seat in a motor vehicle as well as otherseats in transportation vehicles or seats in non-transportationapplications.

[0119] Weight measuring means such as the sensors 6 and 7 are associatedwith the seat, e.g., mounted into or below the seat portion 2 or on theseat structure, for measuring the weight applied onto the seat. Theweight may be zero if no occupying item is present. Sensors 6 and 7 mayrepresent a plurality of different sensors which measure the weightapplied onto the seat at different portions thereof or for redundancypurposes, e.g., such as by means of an airbag 7 in the seat portion 2.Such sensors may be in the form of strain, force or pressure sensorswhich measure the force or pressure on the seat or seat back,displacement measuring sensors which measure the displacement of theseat surface or the entire seat such as through the use of strain gagesmounted on the seat structural members, such as 7, or other appropriatelocations, or systems which convert displacement into a pressure whereina pressure sensor can be used as a measure of weight and/or weightdistribution.

[0120] Many practical problems have arisen during the development stagesof bladder and strain gage based weight systems. Some of these problemsrelate to bladder sensors and in particular to gas filled bladdersensors and are effectively dealt with in U.S. Pat. Nos. 5,918,696,5,927,427, 5,957,491, 5,979,585, 5,984,349, 6,021,863, 6,056,079,6,076,853, 6,260,879 and 6,286,861, all of which are incorporated hereinby reference. Other problems relate to seatbelt usage and tounanticipated stresses and strains that occur in seat mountingstructures.

[0121] As to the latter issue, when an occupant or object is strappedinto the seat using a seatbelt, it can cause an artificial load on abladder type weight sensor and/or strain gage type weight sensors whenthe seatbelt anchorage points are not on the seat. The effects ofseatbelt load can be separated from the effects of object or occupantweight, as disclosed in U.S. Pat. No. 6,242,701, cross-referenced above,if the time varying signals are considered rather than merely usingaveraging to obtain the static load. If a vehicle-mounted verticalaccelerometer is present, then the forcing function on the seat causedby road roughness, steering maneuvers, and the vehicle suspension systemcan be compared with the response of the seat as measured by the bladderor strain gage weight sensors. Through mathematical analysis, themagnitude of the bladder pressure or strain caused by seat belt loadscan be separated from pressure and strain caused by occupant or objectmass. Also, since animated objects such as people cannot sit stillindefinitely, such occupants can be distinguished from inanimate objectsby similarly observing the change in pressure and strain distributionover time.

[0122] A serious problem that has plagued researchers attempting toadapt strain gage technology to seat weight sensing arises from factthat a typical automobile seat is an over-determined structurecontaining indeterminate stresses and strains in the supportingstructure. This arises from a variety of causes such as the connectionbetween the seat structure and the slide mechanisms below the seat orbetween the slide mechanisms and the floor which induces twisting andbending moments in the seat structural members. Similarly, since mostseats have four attachment points and since only three points arenecessary to determine a plane, there can be an unexpected distributionof compression and tensile stresses in the support structure. Tocomplicate the situation, these indeterminable stresses and strains canvary as a function of seat position and temperature. The combination ofall of these effects produces a significant error in the calculation ofthe weight of an occupying item and the distribution of this weight.

[0123] This problem can be solved by looking at changes in pressure andstrain readings in addition to the absolute values. The dynamic responseof an occupied seat is a function of the mass of the occupying item. Asthe car travels down the road, a forcing function is provided to theseat which can be measured by the vertical acceleration component andother acceleration components. This provides a method of measuring theresponse of the seat as well as the forcing function and therebydetermining the mass of occupying item.

[0124] For example, when an occupant first enters the vehicle and sitson a seat, the change in pressure and/or strain measurements willprovide an accurate measurement of the occupant's weight. This accuracydeteriorates as soon as the occupant attaches a seatbelt and/or movesthe seat to a new position. Nevertheless, the change in occupancy of theseat is a significant event that can be easily detected and if thechange in pressure and strain measurements are used as the measurementof the occupant weight, then the weight can be accurately determined.Similarly, the sequence of events for attaching a child seat to avehicle is one that can be easily discerned since the seat is firstplaced into the vehicle and the seat belt cinched followed by placingthe child in the seat or, alternately, the child and seat are placed inthe vehicle followed by a cinching of the seatbelt. Either of theseevent sequences gives a high probability of the occupancy being a childin a child seat. This decision can be confirmed by dynamicalmeasurements as described above.

[0125] A control system for controlling a component of the vehicle basedon occupancy of the seat in accordance with the invention may comprise aplurality of strain gages, or bladder chambers, mounted in connectionwith the seat, each measuring strain or pressure of a respectivelocation caused by occupancy of the seat, and a processor coupled to thestrain or pressure gages and arranged to determine the weight of anoccupying item based on the strain or pressure measurements from thestrain or pressure gages over a period of time, i.e., dynamicmeasurements. The processor controls the vehicle component based atleast in part on the determined weight of the occupying item of theseat. The processor can also determine motion of the occupying item ofthe seat based on the strain or pressure measurements from the strain orpressure gages over the period of time. One or more accelerometers maybe mounted on the vehicle for measuring acceleration in which case, theprocessor may control the component based at least in part on thedetermined weight of the occupying item of the seat and the accelerationmeasured by the accelerometer(s). (See the discussion below in referenceto FIG. 23.)

[0126] By comparing the output of various sensors in the vehicle, it ispossible to determine activities that are affecting parts of the vehiclewhile not affecting other parts. For example, by monitoring the verticalaccelerations of various parts of the vehicle and comparing theseaccelerations with the output of strain gage load cells placed on theseat support structure, or bladder sensors, a characterization can bemade of the occupancy of the seat. Not only can the weight of an objectoccupying the seat be determined, but also the gross motion of such anobject can be ascertained and thereby an assessment can be made as towhether the object is a life form such as a human being and whether theseatbelt is engaged. Strain gage weight sensors are disclosed, forexample, in U.S. Pat. No. 6,242,701, which is incorporated herein byreference in its entirety as if the entire patent were printed herein.In particular, the inventors contemplate the combination of all of theideas expressed in the '701 patent with those expressed in the currentinvention.

[0127] Thus, the combination of the outputs from these accelerometersensors and the output of strain gage or bladder weight sensors in avehicle seat, or in or on a support structure of the seat, can be usedto make an accurate assessment of the occupancy of the seat anddifferentiate between animate and inanimate occupants as well asdetermining where in the seat the occupants are sitting and whether theseatbelt is engaged. This can be done by observing the accelerationsignals from the sensors of FIG. 23 and simultaneously the dynamicstrain gage measurements from seat-mounted strain or pressure gages orpressure measurements of bladder weight sensors. The accelerometersprovide the input function to the seat and the strain gages measure thereaction of the occupying item to the vehicle acceleration and therebyprovide a method of determining dynamically the mass of the occupyingitem and its location. This is particularly important during occupantposition sensing during a crash event. By combining the outputs of theaccelerometers and the strain gages and appropriately processing thesame, the mass and weight of an object occupying the seat can bedetermined as well as the gross motion of such an object so that anassessment can be made as to whether the object is a life form such as ahuman being and whether a seatbelt is used and if so how tightly it iscinched.

[0128] As shown in FIG. 2, there are provided four sets ofwave-receiving sensor systems 11-14 mounted within the passengercompartment. Each set of sensor systems 11-14 comprises a transmitterand a receiver, which may be integrated into a single unit or individualcomponents separated from one another. In this embodiment, the sensorsystem 11 is mounted on the upper portion of the front pillar, A-Pillar,of the vehicle. The sensor system 12 is mounted on the upper portion ofthe intermediate pillar, B-Pillar. The sensor system 13 is mounted onthe roof ceiling portion or the headliner (FIG. 2). The sensor system 14is mounted near the middle of an instrument panel 17 in front of thedriver's seat 16 (FIG. 2). The sensor systems are preferably ultrasonicor electromagnetic. Although sensor systems 11-14 are described as beingultrasonic or electromagnetic sensors, the invention is equallyapplicable for other types of sensors (other than ultrasonic orelectromagnetic) which will detect the presence of an occupant from adistance including capacitive, electric field or other electromagneticsensors. Also, if the sensor systems 11-14 are passive infrared sensors,then they may only comprise a wave-receiver.

[0129] The ultrasonic or electromagnetic sensor systems 11-14 arecontrolled or driven, one at a time or simultaneously, by an appropriatedriver circuit such as ultrasonic or electromagnetic sensor drivercircuit 18 shown in FIG. 3. The transmitters of the ultrasonic orelectromagnetic sensor systems 11-14 transmit respective ultrasonic orelectromagnetic waves toward the seat 1 and transmit pulses (see FIG.4(c)) in sequence at times t1, t2, t3 and t4 (t4>t3>t2>t1) orsimultaneously (t1=t2=t3=t4) The reflected waves of the ultrasonic orelectromagnetic waves are received by the receivers ChA-ChD of theultrasonic or electromagnetic sensors 11-14. The receiver ChA isassociated with the ultrasonic or electromagnetic sensor system 13, thereceiver ChB is associated with the ultrasonic or electromagnetic sensorsystem 14, the receiver ChD is associated with the ultrasonic orelectromagnetic sensor system 11, and the receiver ChD is associatedwith the ultrasonic or electromagnetic sensor system 12.

[0130] The following discussion will apply to the case where ultrasonicsensors are used although a similar discussion can be presented relativeto the use of electromagnetic sensors such as active infrared sensors,taking into account the differences in the technologies. Also, thefollowing discussion will relate to an embodiment wherein the seat 1 isthe front passenger seat. FIGS. 4(a) and 4(b) show examples of thereflected ultrasonic waves USRW that are received by receivers ChA-ChD.FIG. 4(a) shows an example of the reflected wave USRW that is obtainedwhen an adult sits in a normally seated space on the passenger seat 1,while FIG. 4(b) shows an example of the reflected wave USRW that areobtained when an adult sits in a slouching state (one of the abnormalseated-states) in the passenger seat 1.

[0131] In the case of a normally seated passenger, as shown in FIG. 2,the location of the ultrasonic sensor system 12 is closest to thepassenger A. Therefore, the reflected wave pulse P1 is received earliestafter transmission by the receiver ChD as shown in FIG. 4(a), and thewidth of the reflected wave pulse P1 is larger. Next, the distance fromthe ultrasonic sensor 13 is closer to the passenger A, so a reflectedwave pulse P2 is received earlier by the receiver ChA compared with theremaining reflected wave pulses P3 and P4. Since the reflected wavepauses P3 and P4 take more time than the reflected wave pulses P1 and P2to arrive at the receivers ChC and ChB, the reflected wave pulses P3 andP4 are received as the timings shown in FIG. 4(a). More specifically,since it is believed that the distance from the ultrasonic sensor system11 to the passenger A is slightly shorter than the distance from theultrasonic sensor system 14 to the passenger A, the reflected wave pulseP3 is received slightly earlier by the receiver ChC than the reflectedwave pulse P4 is received by the receiver ChB.

[0132] In the case where the passenger A is sitting in a slouching statein the passenger seat 1, the distance between the ultrasonic sensorsystem 11 and the passenger A is shortest. Therefore, the time fromtransmission at time t3 to reception is shortest, and the reflected wavepulse P3 is received by the receiver ChC, as shown in FIG. 4(b). Next,the distances between the ultrasonic sensor system 14 and the passengerA becomes shorter, so the reflected wave pulse P4 is received earlier bythe receiver ChB than the remaining reflected wave pulses P2 and P1.When the distance from the ultrasonic sensor system 13 to the passengerA is compared with that from the ultrasonic sensor system 12 to thepassenger A, the distance from the ultrasonic sensor system 13 to thepassenger A becomes shorter, so the reflected wave pulse P2 is receivedby the receiver ChA first and the reflected wave pulse 1 is thusreceived last by the receiver ChD.

[0133] The configurations of the reflected wave pulses P1-P4, the timesthat the reflected wave pulses P1-P4 are received, the sizes of thereflected wave pulses P1-P4 are varied depending upon the configurationand position of an object such as a passenger situated on the frontpassenger seat 1. FIGS. 4(a) and (b) merely show examples for thepurpose of description and therefore it is a matter of course that thepresent invention is not limited to these examples.

[0134] The outputs of the receivers ChA-ChD, as shown in FIG. 3, areinput to a band pass filter 20 through a multiplex circuit 19 which isswitched in synchronization with a timing signal from the ultrasonicsensor drive circuit 18. The band pass filter 20 removes a low frequencywave component from the output signal based on each of the reflectedwave USRW and also removes some of the noise. The output signal based oneach of the reflected wave USRW is passed through the band pass filter20, then is amplified by an amplifier 21. The amplifier also removes thehigh frequency carrier wave component in each of the reflected USRW andgenerates an envelope wave signal. This envelope wave signal is input toan analog/digital converter (ADC) 22 and digitized as measured data. Themeasured data is input to a processing circuit 23, which is controlledby the timing signal which is in turn output from the ultrasonic sensordrive circuit 18.

[0135] The processing circuit 23 collects measured data at intervals of7 ms, and 47 data points are generated for each of the ultrasonic sensorsystems 11-14. For each of these reflected waves USRW, the initialreflected wave portion T1 and the last reflected wave portion T2 are cutoff. The reason for this will be described when the training procedureof a neural network circuit is described later, and the description isomitted for now. With this, 32 data points, 31 data points, 37 datapoints, and 38 data points will be sampled by the ultrasonic sensorsystems 11, 12, 13 and 14, respectively. The reason why the number ofdata points differs for each of the ultrasonic sensor systems 11 - 14 isthat the distance from the passenger seat 1 to the ultrasonic sensorsystems 11-14 differ from one another.

[0136] Each of the measured data is input to a normalization circuit 24and normalized. The normalized measured data is input to the neuralnetwork circuit 25 as wave data.

[0137] The output of the weight sensor(s) 6 and 7 is amplified by anamplifier 26 coupled to the weight sensor(s) 6 and 7 and the amplifiedoutput is input to the analog/digital converter 27.

[0138] The reclining angle detecting sensor 9 and the seat trackposition-detecting sensor 10, which each may comprise a variableresistor, and can be connected to constant-current circuits,respectively. A constant-current can be supplied from theconstant-current circuit to the reclining angle detecting sensor 9, andthe reclining angle detecting sensor 9 converts a change in theresistance value on the tilt of the back portion 3 to a specificvoltage. This output voltage is input to an analog/digital converter 28as angle data, i.e., representative of the angle between the backportion 3 and the seat portion 2. Similarly, a constant current can besupplied from the constant-current circuit to the seat trackposition-detecting sensor 10 and the seat track position detectingsensor 10 converts a change in the resistance value based on the trackposition of the seat portion 2 to a specific voltage. This outputvoltage is input to an analog/digital converter 29 as seat track data.Thus, the outputs of the reclining angle-detecting sensor 9 and the seattrack position-detecting sensor 10 are input to the analog/digitalconverters 28 and 29, respectively. Each digital data value from theADCs 28,29 is input to the neural network circuit 25. Although thedigitized data of the weight sensor(s) 6 and 7 is input to the neuralnetwork circuit 25, the output of the amplifier 26 is also input to acomparison circuit. The comparison circuit, which is incorporated in thegate circuit algorithm, determines whether or not the weight of anobject on the passenger seat 1 is more than a predetermined weight, suchas 60 lbs., for example. When the weight is more than 60 lbs., thecomparison circuit outputs a logic 1 to the gate circuit to be describedlater. When the weight of the object is less than 60 lbs., a logic 0 isoutput to the gate circuit.

[0139] A heartbeat sensor 31 is arranged to detect a heartbeat, and themagnitude thereof, of a human occupant of the seat, if such a humanoccupant is present. The output of the heartbeat sensor 31 is input tothe neural network circuit 25. The heartbeat sensor 31 may be of thetype as disclosed in McEwan (U.S. Pat. Nos. 5,573,012 and 5,766,208which are incorporated herein in their entirety by reference) ) or basedon noise radar technology. The heartbeat sensor 31 can be positioned atany convenient position relative the seat 1 where occupancy is beingmonitored. A preferred location is within the vehicle seatback for anMIR and in the headliner for a noise radar type device.

[0140] A capacitive or electric field sensor 32 is arranged to detectthe presence of an occupying item on the seat 1 and the output thereofis input to the neural network circuit 25. Capacitor or electric fieldsensors appropriate for this function are disclosed in Kithil (U.S. Pat.No. 5,602,734, which is incorporated herein by reference) and Jinno etal (U.S. Pat. No. 5,948,031, which is incorporated herein by reference).Capacitive sensors can in general be mounted at locations 11-14 in FIG.2 or in the vehicle seat or seatback although by their nature they canoccupy considerably more space than shown in the drawings.

[0141] A motion sensor 33 is arranged to detect motion of an occupyingitem on the seat 1 and the output thereof is input to the neural networkcircuit 25. Motion sensors can utilize a micro-power impulse radar (MIR)system as disclosed, for example, in McEwan (U.S. Pat. No. 5,361,070,which is incorporated herein by reference), as well as many otherpatents by the same inventor or by noise radar. Motion sensing isaccomplished by monitoring a particular range from the sensor asdisclosed in that patent. MIR is one form of radar which hasapplicability to occupant sensing and can be mounted at locations suchas 11-14 in FIG. 2. It has an advantage over ultrasonic sensors in thatdata can be acquired at a higher speed and thus the motion of anoccupant can be more easily tracked. The ability to obtain returns overthe entire occupancy range is somewhat more difficult than withultrasound resulting in a more expensive system overall. MIR or noiseradar has additional advantages in lack of sensitivity to temperaturevariation and can have a comparable resolution to about 40 kHzultrasound. Resolution comparable to higher frequency is also feasible.Additionally, multiple MIR sensors can be used when high speed trackingof the motion of an occupant during a crash is required since they canbe individually pulsed without interfering with each other through timeor code division multiplexing.

[0142] The neural network circuit 25 recognizes the seated-state of apassenger A by training as described in several books on Neural Networksreferenced in the above referenced patents and patent applications.Then, after training the seated-state of the passenger A and developingthe neural network weights, the system is tested. The training procedureand the test procedure of the neural network circuit 25 will hereafterbe described with a flowchart shown in FIG. 6.

[0143] As diagrammed in FIG. 6, the first step is to mount the four setsof ultrasonic sensor systems 11-14, the weight sensors 6 and 7, thereclining angle detecting sensor 9, and the seat track positiondetecting sensor 10 into a vehicle (step S1). Next, in order to providedata for the neural network circuit 25 to learn the patterns of seatedstates, data is recorded for patterns of all possible seated states anda list is maintained recording the seated states for which data wasacquired. The data from the sensors/transducers 6, 7, 9-14 and 31-33,for a particular occupancy of the passenger seat is called a vector(step S2). It should be pointed out that the use of the reclining angledetecting sensor 9, seat track position detecting sensor 10, heartbeatsensor 31, capacitive sensor 32 and motion sensor 33 are not essentialto the detecting apparatus and method in accordance with the invention.However, each of these sensors, in combination with any one or more ofthe other sensors enhances the evaluation of the seated-state of theseat.

[0144] For the vectors of data, adults and children each with differentpostures, states of windows etc. within the passenger compartment, andoccupied and unoccupied child seats were selected. The selected adultsinclude people with a variety of different physiques such as fat, lean,small, large, tall, short, and glasses wearing persons. The selectedchildren ranged from an infant to a large child (for example, about 14year old). In addition, the selected postures include, for example, asitting state with legs crossed on a seat, a sitting state with legs onan instrument panel, a sitting state while reading a newspaper, a book,or a map, a sitting state while holding a cup of coffee, a cellulartelephone or a dictation machine, and a slouching state with and withoutraised knees. Furthermore, the selected compartment states includevariations in the seat track position, the window-opening amount,headrest position, and varying positions of a sun-visor. Moreover, amultitude of different models of child seats are used in the forwardfacing position and, where appropriate, in a rear facing position. Inthis example, the range of weights and the corresponding normalizedvalues are as follows: Class Weight Range Normalized Value Empty Seat 0to 2.2 lbs. 0 to 0.01 Rear Facing Child Seat 2.2 to 60 lbs. 0.01 to 0.27Forward Facing Child Seat 2.2 to 60 lbs. 0.01 to 0.27 Normal PositionAdult 60 lbs and greater 0.27 to 1

[0145] Obviously, other weight ranges may also be used in accordancewith the invention and each weight range may be tailored to specificconditions, such as different vehicles. The output of the weight sensorsmay not correspond directly to be weight ranges in the above table. Iffor example strain measuring sensors are placed on each of the vehicleseat supports, such sensors will also respond to the weight of the seatitself That weight must therefore the remove so that only the additionalweight of an occupying item is measured. Similarly it may be desirableto place strain-sensing devices on only some of the vehicle seat supportstructures. In such cases the weight of the occupying item can be ininferred from the output of the strain sensing sensors. This will bedescribed in greater detail below.

[0146] Various vehicle setups were prepared by a combination of thesevariations and, for in this embodiment, almost 500,000 or more vectorsshould be prepared for the patterns to be used as data for the neuralnetwork training.

[0147] Next, based on the training data from the reflected waves of theultrasonic sensor systems 11-14 and the other sensors 6, 7,31-33, thevector data is collected (step S3). Next, the reflected waves P1-P4 aremodified by removing the initial reflected waves with a short reflectiontime from an object (range gating) (period T1 in FIG. 5) and the lastportion of the reflected waves with a long reflection time from anobject (period P2 in FIG. 5) (step S4). It is believed that thereflected waves with a short reflection time from an object is a due tocross-talk, that is, waves from the transmitters which leaks into eachof their associated receivers ChA-ChD. It is also believed that thereflected waves with a long reflection time are reflected waves from anobject far away from the passenger seat or from multipath reflections.If these two reflected wave portions are used as data, they will addnoise to the training process. Therefore, these reflected wave portionsare eliminated from the data.

[0148] As shown in FIG. 7(a), measured data is normalized by making thepeaks of the reflected wave pulses P1-4 equal (step S5). This eliminatesthe effects of different reflectivities of different objects and peopledepending on the characteristics of their surfaces such as theirclothing Data from the weight sensor, seat track position sensor andseat recling angle sensor are also frequently normalized based typicallyon fixed normalization parameters.

[0149] The data from the transducers are now also preferably fed througha logaritmic or equivalent compression circuit that substantiallyreduces the magnitude of reflected signals from high reflectivitytargets compared to those of low reflectivity. Additionally, a time gaincircuit is used to compensate for the difference in sonic strengthreceived by the transducer based on the distance of the reflectingobject from the transducer.

[0150] Therefore, the normalized data from the ultrasonic transducersthe seat track position detecting sensor 10, the reclining angledetecting sensor 9, from the weight sensor(s) 6 and 7, from theheartbeat sensor 31, the capacitive sensor 32 and the motion sensor 33are input to the neural network circuit 25, and the neural networkcircuit 25 is then trained on this data. More specifically, the neuralnetwork circuit 25 adds up the normalized data from the ultrasonictransducers, from the seat track position detecting sensor 10, from thereclining angle detecting sensor 9, from the weight sensor(s) 6 and 7,from the heartbeat sensor 31, from the capacitive sensor 32 and from themotion sensor 33 with each data point multiplied by a associated weightaccording to the conventional neural network process to determinecorrelation function (step S6).

[0151] In this embodiment, 144 data points are appropriatelyinterconnected at 25 connecting points of layer 1, and each data pointis mutually correlated through the neural network training and weightdetermination process. The 144 data points consist of 138 measured datapoints from the ultrasonic transducers, the data (139th) from the seattrack position detecting sensor 10, the data (140th) from the recliningangle detecting sensor 9, the data (141st) from the weight sensor(s) 6,the data (142 ^(nd)) from the heartbeat sensor 31, the data (143 ^(rd))from the capacitive sensor and the data (144 ^(th)) from the motionsensor. Each of the connecting points of the layer 1 has an appropriatethreshold value, and if the sum of measured data exceeds the thresholdvalue, each of the connecting points will output a signal to theconnecting points of layer 2. Although the weight sensor input is shownas a single input, in general there will be a separate input from eachweight sensor used. For example, if the seat has four seat supports andif a strained measuring element is used on each support, what will befour data inputs to neural network.

[0152] The connecting points of the layer 2 comprises 20 points, and the25 connecting points of the layer 1 are appropriately interconnected asthe connecting points of the layer 2. Similarly, each data is mutuallycorrelated through the training process and weight determination asdescribed above and in the above referenced neural network texts. Eachof the 20 connecting points of the layer 2 has an appropriate thresholdvalue, and if the sum of measured data exceeds the threshold value, eachof the connecting points will output a signal to the connecting pointsof layer 3.

[0153] The connecting points of the layer 3 comprises 3 points, and theconnecting points of the layer 2 are interconnected at the connectingpoints of the layer 3 so that each data is mutually correlated asdescribed above. If the sum of the outputs of the connecting points oflayer 2 exceeds a threshold value, the connecting points of the latter 3will output Logic values (100), (010), and (001) respectively, forexample.

[0154] The threshold value of each connecting point is determined bymultiplying weight coefficients and summing up the results in sequence,and the aforementioned training process is to determine a weightcoefficient Wj so that the threshold value (ai) is a previouslydetermined output.

ai=ΣWj·Xj (j=1 to N)

[0155] wherein Wj is the weight coefficient,

[0156] Xj is the data and

[0157] N is the number of samples.

[0158] Based on this result of the training, the neural network circuit25 generates the weights for the coefficients of the correlationfunction or the algorithm (step S 7).

[0159] At the time the neural network circuit 25 has learned a suitablenumber of patterns of the training data, the result of the training istested by the test data. In the case where the rate of correct answersof the seated-state detecting unit based on this test data isunsatisfactory, the neural network circuit is further trained and thetest is repeated. In this embodiment, the test was performed based onabout 600,000 test patterns. When the rate of correct test resultanswers was at about 98%, the training was ended.

[0160] The neural network circuit 25 has outputs 25 a, 25 b and 25 c.Each of the outputs 25 a, 25 b and 25 c outputs a signal of logic 0 or 1to a gate circuit or algorithm 30. Based on the signals from the outputs25 a, 25 b and 25 c, any one of these combination (100), (010) and (001)is obtained. In another preferred embodiment, all data for the emptyseat was removed from the training set and the empty seat case wasdetermined based on the output of the weight sensor alone. Thissimplifies the neural network and improves its accuracy.

[0161] In this embodiment, the output (001) correspond to a vacant seat,a seat occupied by an inanimate object or a seat occupied by a pet(VACANT), the output (010) corresponds to a rear facing child seat(RFCS) or an abnormally seated passenger (ASP), and the output (100)corresponds to a normally seated passenger (NSP) or a forward facingchild seat (FFCS).

[0162] The gate circuit (seated-state evaluation circuit) 30 can beimplemented by an electronic circuit or by a computer algorithm by thoseskilled in the art and the details will not be presented here. Thefunction of the gate circuit 30 is to remove the ambiguity thatsometimes results when ultrasonic sensors and seat position sensorsalone are used. This ambiguity is that it is sometimes difficult todifferentiate between a rear facing child seat (RFCS) and an abnormallyseated passenger (ASP), or between a normally seated passenger (NSP) anda forward facing child seat (FFCS). By the addition of one or moreweight sensors in the function of acting as a switch when the weight isabove or below 60 lbs., it has been found that this ambiguity can beeliminated. The gate circuit therefore takes into account the output ofthe neural network and also the weight from the weight sensor(s) asbeing above or below 60 lbs. and thereby separates the two cases justdescribed and results in five discrete outputs.

[0163] Thus, the gate circuit 30 fulfills a role of outputting fivekinds of seated-state evaluation signals, based on a combination ofthree kinds of evaluation signals from the neural network 25 andsuperimposed information from the weight sensor(s). The fiveseated-state evaluation signals are input to an airbag deploymentdetermining circuit that is part of the airbag system and will not bedescribed here. Naturally, as disclosed in the above reference patentsand patent applications, the output of this system can also be used toactivate a variety of lights or alarms to indicate to the operator ofthe vehicle the seated state of the passenger. Naturally, the systemthat has been here described for the passenger side is also applicablefor the most part for the driver side.

[0164] An alternate and preferred method of accomplishing the functionperformed by the gate circuit is to use a modular neural network. Inthis case, the first level neural network is trained on determiningwhether the seat is occupied or vacant. The input to this neural networkconsists of all of the data points described above. Since the onlyfunction of this neural network is to ascertain occupancy, the accuracyof this neural network is very high. If this neural network determinesthat the seat is not vacant, then the second level neural networkdetermines the occupancy state of the seat.

[0165] In this embodiment, although the neural network circuit 25 hasbeen employed as an evaluation circuit, the mapping data of thecoefficients of a correlation function may also be implemented ortransferred to a microcomputer to constitute the valuation circuit (seeStep S 8 in FIG. 6).

[0166] According to the seated-state detecting unit of the presentinvention, the identification of a vacant seat (VACANT), a rear facingchild seat (RFCS), a forward facing child seat (FFCS), a normally seatedadult passenger (NSP), an abnormally seated adult passenger (ASP), canbe reliably performed. Based on this identification, it is possible tocontrol a component, system or subsystem in the vehicle. For example, aregulation valve which controls the inflation or deflation of an airbagmay be controlled based on the evaluated identification of the occupantof the seat. This regulation valve may be of the digital or analog type.A digital regulation valve is one that is in either of two states, openor closed. The control of the flow is then accomplished by varying thetime that the valve is open and closed, i.e., the duty cycle.

[0167] Moreover, the seated-state detecting unit described above may beused in a component adjustment system and method described below whenthe presence of a human being occupying the seat is detected.

[0168] The component adjustment system and methods in accordance withthe invention automatically and passively adjust the component based onthe morphology of the occupant of the seat. As noted above, theadjustment system may include the seated-state detecting unit describedabove so that it will be activated if the seated-state detecting unitdetects that an adult or child occupant is seated on the seat, i.e., theadjustment system will not operate if the seat is occupied by a childseat, pet or inanimate objects. Obviously, the same system can be usedfor any seat in the vehicle including the driver seat and the passengerseat(s). This adjustment system may incorporated the same components asthe seated-state detecting unit described above, i.e., the samecomponents may constitute a part of both the seated-state detecting unitand the adjustment system, e.g., the weight measuring means.

[0169] The adjustment system described herein, although improved overthe prior art, will at best be approximate since two people, even ifthey are identical in all other respects, may have a different preferreddriving position or other preferred adjusted component location ororientation. A system that automatically adjusts the component,therefore, must learn from its errors. Thus, when a new occupant sits inthe vehicle, for example, the system automatically estimates the bestlocation of the component for that occupant and moves the component tothat location, assuming it is not already at the best location. If theoccupant changes the location, the system must remember that change andincorporate it into the adjustment the next time that person enters thevehicle and is seated in the same seat. Therefore, the system need notmake a perfect selection the first time but it must remember the personand the position the component was in for that person. The system,therefore, makes one, two or three measurements of morphologicalcharacteristics of the occupant and then adjusts the component based onan algorithm. The occupant will correct the adjustment and the next timethat the system measures the same measurements for those measurementcharacteristics, it will set the component to the corrected position. Assuch, preferred components for which the system in accordance with theinvention is most useful are those which affect a driver of the vehicleand relate to the sensory abilities of the driver, i.e., the mirrors,the seat, the steering wheel and steering column and accelerator, clutchand brake pedals.

[0170] The first characteristic used is a measurement of the height ofthe occupant from the vehicle seat. This can be done by a sensor in theceiling of the vehicle but this becomes difficult since, even for thesame seat location, the head of the occupant will not be at the sameangle with respect to the seat and therefore the angle to a ceilingmounted sensor is in general unknown at least as long as only oneceiling mounted sensor is used. This problem can be solved if two orthree sensors are used as described in more detail below. An alternateimplementation is to place the sensor in the seat. In the '320 patentmentioned above, a rear impact occupant protection apparatus isdisclosed which uses sensors mounted within the headrest. This samesystem can also be used to measure the height of the occupant from theseat and thus, for no additional cost assuming the rear impact occupantprotection system described in the '320 patent is provided, the firstmeasure of the occupant's morphology can be achieved. For someapplications, this may be sufficient since it is unlikely that twooperators will use the vehicle who have the same height. For otherimplementations, one or more additional measurements are used.Naturally, a face, fingerprint or iris recognition system will have theleast problem identifying a previous occupant.

[0171] Referring now to FIG. 8, an automatic adjustment system foradjusting a seat (which is being used only as an example of a vehiclecomponent) is shown generally at 100 with a movable headrest 111 andultrasonic sensor 120 and ultrasonic receiver 121 for measuring theheight of the occupant of the seat. Power means such as motors 191, 192,and 193 connected to the seat for moving the base of the seat, controlmeans such as a control circuit, system or module 150 connected to themotors and a headrest actuation mechanism using motors 160 and 170,which may be servomotors, are also illustrated. The seat 110 andheadrest 111 are shown in phantom. Vertical motion of the headrest 111is accomplished when a signal is sent from control module 150 toservomotor 160 through a wire 131. Servomotor 160 rotates lead screw 162which engages with a threaded hole in member 164 causing it to move upor down depending on the direction of rotation of the lead screw 162.Headrest support rods 165 and 166 are attached to member 164 and causethe headrest 111 to translate up or down with member 164. In thismanner, the vertical position of the headrest can be controlled asdepicted by arrow A-A. Ultrasonic transmitter and receiver 120,121 maybe replaced by other appropriate wave-generating and receiving devices,such as electromagnetic, active infrared transmitters and receivers.

[0172] Wire 132 leads from control module 150 to servomotor 170 whichrotates lead screw 172. Lead screw 172 engages with a threaded hole inshaft 173 which is attached to supporting structures within the seatshown in phantom. The rotation of lead screw 172 rotates servomotorsupport 161, upon which servomotor 160 is situated, which in turnrotates headrest support rods 165 and 166 in slots 168 and the seat 110.Rotation of the servomotor support 161 is facilitated by a rod 171 uponwhich the servomotor support 161 is positioned. In this manner, theheadrest 111 is caused to move in the fore and aft direction as depictedby arrow B-B. Naturally there are other designs which accomplish thesame effect in moving the headrest up and down and fore and aft.

[0173] The operation of the system is as follows. When an adult or childoccupant is seated on a seat containing the headrest and control systemdescribed above as determined by the neural network circuit 25, theultrasonic transmitter 120 emits ultrasonic energy which reflects off ofthe head of the occupant and is received by receiver 121. An electroniccircuit in control module 150 contains a microprocessor which determinesthe distance from the head of the occupant based on the time between thetransmission and reception of an ultrasonic pulse. Control module 150may be within the same microprocessor as neural network circuit 25 orseparate therefrom. The headrest 111 moves up and down until it findsthe top of the head and then the vertical position closest to the headof the occupant and then remains at that position. Based on the timedelay between transmission and reception of an ultrasonic pulse, thesystem can also determine the longitudinal distance from the headrest tothe occupant's head. Since the head may not be located precisely in linewith the ultrasonic sensors, or the occupant may be wearing a hat, coatwith a high collar, or may have a large hairdo, there may be some errorin this longitudinal measurement.

[0174] When an occupant sits on seat 110, the headrest 111 moves to findthe top of the occupant's head as discussed above. This is accomplishedusing an algorithm and a microprocessor which is part of control circuit150. The headrest 111 then moves to the optimum location for rear impactprotection as described in the above referenced '320 patent. Once theheight of the occupant has been measured, another algorithm in themicroprocessor in control circuit 150 compares the occupant's measuredheight with a table representing the population as a whole and from thistable, the appropriate positions for the seat corresponding to theoccupant's height is selected. For example, if the occupant measured 33inches from the top of the seat bottom, this might correspond to a 85%human, depending on the particular seat and statistical tables of humanmeasurements.

[0175] Careful study of each particular vehicle model provides the datafor the table of the location of the seat to properly position the eyesof the occupant within the “eye-ellipse”, the steering wheel within acomfortable reach of the occupant's hands and the pedals within acomfortable reach of the occupant's feet, based on his or her size, etc.

[0176] Once the proper position has been determined by control circuit150, signals are sent to motors 191, 192, and 193 to move the seat tothat position. If during some set time period after the seat has beenpositioned, the operator changes these adjustments, the new positions ofthe seat are stored in association with an occupant height class in asecond table within control circuit 150. When the occupant againoccupies the seat and his or her height has once again been determined,the control circuit will find an entry in the second table which takesprecedence over the basic, original table and the seat returns to theadjusted position. When the occupant leaves the vehicle, or even whenthe engine is shut off and the door opened, the seat can be returned toa neutral position which provides for easy entry and exit from thevehicle.

[0177] The seat 110 also contains two control switch assemblies 180 and182 for manually controlling the position of the seat 110 and headrest111. The seat control switches 180 permit the occupant to adjust theposition of the seat if he or she is dissatisfied with the positionselected by the algorithm. The headrest control switches 182 permit theoccupant to adjust the position of the headrest in the event that thecalculated position is uncomfortably close to or far from the occupant'shead. A woman with a large hairdo might find that the headrestautomatically adjusts so as to contact her hairdo. This adjustment shemight find annoying and could then position the headrest further fromher head. For those vehicles which have a seat memory system forassociating the seat position with a particular occupant, which has beenassumed above, the position of the headrest relative to the occupant'shead could also be recorded. Later, when the occupant enters thevehicle, and the seat automatically adjusts to the recorded preference,the headrest will similarly automatically adjust (FIG. 17B).

[0178] The height of the occupant, although probably the best initialmorphological characteristic, may not be sufficient especially fordistinguishing one driver from another when they are approximately thesame height. A second characteristic, the occupant's weight, can also bereadily determined from sensors mounted within the seat in a variety ofways as shown in FIG. 9 which is a perspective view of the seat shown inFIG. 8 with a displacement or weight sensor 200 shown mounted onto theseat. Displacement sensor 200 is supported from supports 202 and 204. Ingeneral, displacement sensor 200, or another non-displacement sensor,measures a physical state of a component affected by the occupancy ofthe seat. An occupying item of the seat will cause a force to be exerteddownward and the magnitude of this force is representative of the weightof the occupying item. Thus, by measuring this force, information aboutthe weight of the occupying item can be obtained. A physical state maybe any force changed by the occupancy of the seat and which is reflectedin the component, e.g., strain of a component, compression of acomponent, tension of a component.

[0179] Referring now to FIG. 9A, which is a view of the apparatus ofFIG. 9 taken along line 9A-9A, seat 230 is constructed from a cushion orfoam layer 232 which is supported by a spring system 234 which is incontact and/or association with the displacement sensor 200. As shown,displacement sensor 200 is underneath the spring system 234 but thisrelative positioning is not a required feature of the invention. Thedisplacement sensor 200 comprises an elongate cable 205 retained at oneend by support 210 and a displacement sensor 220 situated at an oppositeend. This displacement sensor 220 can be any of a variety of suchdevices including, but not limited to, a linear rheostat, a linearvariable differential transformer (LVDT), a linear variable capacitor,or any other length measuring device. Alternately, as shown in FIG. 9C,the cable can be replaced with one or more springs 242 retained betweensupports 210 and the tension in the spring measured using a strain gage(conventional wire or foil or a SAW strain gage) or other forcemeasuring device 244 or the strain in the seat support structure can bemeasured by appropriately placing strain gages on one or more of theseat supports as described in more detail below. The strain gage orother force measuring device could be arranged in association with thespring system 234 and could measure the deflection of the bottom surfaceof the cushion or foam layer 232.

[0180] When a SAW strain gage 244 is used as part of weight sensor 200,an interrogator 246 could be placed on the vehicle to enable wirelesscommunication and/or power transfer to the SAW strain gage 244. As such,when it is desired to obtain the force being applied by the occupyingitem on the seat, the interrogator 246 sends a radio signal to the SAWstrain gage causing it to transmit a return signal with the measuredstrain of the spring 242. Interrogator 246 is coupled to the processorused to determine the control of the vehicle component.

[0181] As shown in FIG. 9D, one or more SAW strain gages 248 could alsobe placed on the bottom surface of a seat support pan 247 for thosevehicles using this construction in order to measure the deflection ofthe bottom surface of support pan 247 which is representative of theweight of the occupying item to the seat. An interrogator 249 could alsobe used in this embodiment.

[0182] One seat design is illustrated in FIG. 9. Similar weightmeasurement systems can be designed for other seat designs. Also, someproducts are available which can approximately measure weight based onpressure measurements made at or near the upper seat surface 236. Itshould be noted that the weight measured here will not be the entireweight of the occupant since some of the occupant's weight will besupported by his or her feet which are resting on the floor or pedals.As noted above, the weight may also be measured by the weight sensor(s)6 and 7 described above in the seated-state detecting unit.

[0183] As weight is placed on the seat surface 236, it is supported byspring 234 which deflects downward causing cable 205 of the sensor 200to begin to stretch axially. Using a LVDT as an example of lengthmeasuring device 220, the cable 205 pulls on rod 221 tending to removerod 221 from cylinder 223 (FIG. 9B). The movement of rod 221 out ofcylinder 223 is resisted by a spring 222 which returns the rod 221 intothe cylinder 223 when the weight is removed from the seat surface 236.The amount which the rod 221 is removed from the cylinder 223 ismeasured by the amount of coupling between the windings 226 and 227 ofthe transformer as is well understood by those skilled in the art.LVDT's are commercially available devices. In this matter, thedeflection of the seat can be measured which is a measurement of theweight on the seat. The exact relationship between weight and LVDToutput is generally determined experimentally for this application. Analternative weight measuring apparatus will be discussed below.

[0184] SAW strain gages could also be used to determine the downwarddeflection of the spring 234 and the deflection of the cable 205.

[0185] By use of a combination of weight and height, the driver of thevehicle can in general be positively identified among the class ofdrivers who operate the vehicle. Thus, when a particular driver firstuses the vehicle, the seat will be automatically adjusted to the properposition. If the driver changes that position within a prescribed timeperiod, the new seat position will be stored in the second table for theparticular driver's height and weight. When the driver reenters thevehicle and his or her height and weight are again measured, the seatwill go to the location specified in the second table if one exists.Otherwise, the location specified in the first table will be used.

[0186] The system described above is based on the assumption that theoccupant will be satisfied with one seat position throughout an extendeddriving trip. Studies have shown that for extended travel periods thatthe comfort of the driver can be improved through variations in the seatposition. This variability can be handled in several ways. For example,the amount and type of variation preferred by an occupant of theparticular morphology can be determined through case studies and focusgroups. If it is found, for example, that the 50 percentile male driverprefers the seatback angle to vary by 5 degrees sinusodially with aone-hour period, this can be programmed to the system. Since the systemknows the morphology of the driver, it can decide from a lookup table oralgorithm (trained or not) what is the best variability for the averagedriver of that morphology. The driver then can select from severalpreferred possibilities if, for example, he or she wishes to have theseatback not move at all or follow an excursion of 10 degrees over twohours.

[0187] This system provides an identification of the driver based on twomorphological characteristics which is adequate for most cases. Asadditional features of the vehicle interior identification andmonitoring system described in the above referenced patent applicationsare implemented, it will be possible to obtain additional morphologicalmeasurements of the driver which will provide even greater accuracy indriver identification. Two characteristics may not be sufficient to relyon for theft and security purposes, however, many other driverpreferences can still be added to seat position with this level ofoccupant recognition accuracy. These include the automatic selection ofa preferred radio station, vehicle temperature, steering wheel andsteering column position, etc.

[0188] One advantage of using only the height and weight is that itavoids the necessity of the seat manufacturer from having to interactwith the headliner manufacturer, or other component suppliers, since allof the measuring transducers are in the seat. This two characteristicsystem is generally sufficient to distinguish drivers that normallydrive a particular vehicle. This system costs little more than thememory systems now in use and is passive, i.e., it does not requireaction on the part of the occupant after his initial adjustment has beenmade.

[0189] Instead of measuring the height and weight of the occupant, it isalso possible to measure a combination of any two morphologicalcharacteristics and during a training phase, derive a relationshipbetween the occupancy of the seat, e.g., adult occupant, child occupant,etc., and the data of the two morphological characteristic. Thisrelationship may be embodied within a neural network so that during use,by measuring the two morphological characteristics, the occupancy of theseat can be determined.

[0190] Naturally, there are other methods of measuring the height of thedriver such as placing the transducers at other locations in thevehicle. Some alternatives are shown in FIG. 10 which is a side planview wherein two height measuring sensors 320, 321 are shown, sensor 321being mounted into the headliner above the occupant's head and the othersensor 320 being mounted onto the A-pillar. A sensor as used herein isthe combination of two transducers (a transmitter and a receiver) or onetransducer which can both transmit and receive. The headliner is thetrim which provides the interior surface to the roof of the vehicle andthe A-pillar is the roof-supporting member which is on either side ofthe windshield and on which the front doors are hinged. Thesetransducers may already be present because of other implementations ofthe vehicle interior identification and monitoring system described inthe above referenced patent applications. In this case, the use of bothtransducers provides a more accurate determination of location of thehead of the driver. Using transducer 321 alone, the exact position ofthe head is ambiguous since the transducer measures the distance to thehead regardless of what direction the head is. By knowing the distancefrom the head to transducer 320, the ambiguity is substantially reduced.This argument is of course dependent on the use of ultrasonictransducers. Optical transducers using CCD or CMOS arrays are nowbecoming price competitive and, as pointed out in the above referencedpatent applications, will be the technology of choice for interiorvehicle monitoring. A single CCD array of 160 by 160 pixels, forexample, coupled with the appropriate pattern recognition software, canbe used to form an image of the head of an occupant and accuratelylocate the head for the purposes of this invention. It can also be usedwith a face recognition algorithm to positively identify the occupant.

[0191]FIG. 10 also illustrates a system where the seatbelt 330 has anadjustable upper anchorage point 331 which is automatically adjusted bya motor 332 to a location optimized based on the height of the occupant.The calculations for this feature and the appropriate control circuitrycan also be located in control module 301 or elsewhere if appropriate.

[0192] Many luxury automobiles today have the ability to control theangle of the seat back as well as a lumbar support. These additionalmotions of the seat can also be controlled by the seat adjustment systemin accordance with the invention. FIG. 11 is a view of the seat of FIG.8 showing motors 481 and 482 for changing the tilt of the seat back andthe lumbar support. Three motors 482 are used to adjust the lumbarsupport in this implementation. The same procedure is used for theseadditional motions as described for FIG. 8 above.

[0193] An initial table is provided based on the optimum positions forvarious segments of the population. For example, for some applicationsthe table may contain a setting value for each five percentile of thepopulation for each of the 6 possible seat motions, fore and aft, up anddown, total seat tilt, seat back angle, lumbar position, and headrestposition for a total of 120 table entries. The second table similarlywould contain the personal preference modified values of the 6 positionsdesired by a particular driver.

[0194] In FIG. 8, the ultrasonic transducers 120 and 121 were describedas one being a transmitter and the other being a receiver. For someapplications, it is desirable to use both transducers as bothtransducers and receivers. Similarly, a third combination transmitterand receiver 122 may also be utilized as shown in FIG. 11. Thisarrangement permits many of the advantages of a phased array system tobe achieved.

[0195] The angular resolution of a transducer is proportional to theratio of the wavelength to the diameter of the transmitter. Once threetransmitters and receivers are used, the approximate equivalent singletransmitter and receiver is one which has a diameter approximately equalto the shortest distance between any pair of transducers. In this case,the equivalent diameter is equal to the distance between transmitter 120or 121 and 122. This provides far greater resolution and, by controllingthe phase between signals sent by the transmitters, the direction of theequivalent ultrasonic beam can be controlled. Thus, the head of thedriver can be scanned with great accuracy and a map made of theoccupant's head. Using this technology plus an appropriate patternrecognition algorithm, such as a neural network, an accurate location ofthe driver's head can be found even when the driver's head is partiallyobscured by a hat, coat, or hairdo. This also provides at least oneother identification morphological characteristic which can be used tofurther identify the occupant, namely the diameter of the driver's head.

[0196] With knowledge of the weight of an occupant, additionalimprovements can be made to automobile and truck seat designs. Inparticular, the stiffness of the seat can be adjusted so as to providethe same level of comfort for light and for heavy occupants. The dampingof occupant motions, which heretofore has been largely neglected, canalso be readily adjusted as shown on FIG. 12 which is a view of the seatof FIG. 8 showing one of several possible arrangements for changing thestiffness and the damping of the seat. In the seat bottom 520, there isa container 515, the conventional foam and spring design has beenreplaced by an inflated rectangular container very much like an airmattress which contains a cylindrical inner container 518 which isfilled with an open cell urethane foam. An adjustable orifice 525connects the two container 515,518 so that air can flow in a controlledmanner therebetween. The amount of opening of orifice 525 is controlledby control circuit 150. A small air compressor 555 controls the pressurein container 515 under control of the control circuit 150. A pressuretransducer 560 monitors the pressure within container 515 and inputsthis information into control circuit 150.

[0197] The operation of the system is as follows. When an occupant sitson the seat, pressure initially builds up in the seat container 515which gives an accurate measurement of the weight of the occupant.Control circuit 150, using an algorithm and a microprocessor, thendetermines an appropriate stiffness for the seat and adds pressure toachieve that stiffness. The pressure equalizes between the twocontainers 515 and 518 through the flow of air through orifice 525.Control circuit 150 also determines an appropriate damping for theoccupant and adjusts the orifice 525 to achieve that damping. As thevehicle travels down the road and the road roughness causes the seat tomove up and down, the inertial force on the seat by the occupant causesthe air pressure to rise and fall in container 518 and also, but, muchless so, in container 515 since the occupant sits mainly above container518 and container 515 is much larger than container 518. The majordeflection in the seat takes place first in container 518 whichpressurizes and transfers air to container 515 through orifice 525. Thesize of the orifice opening determines the flow rate between the twocontainers and therefore the damping of the motion of the occupant.Since this opening is controlled by control circuit 150, the amount ofdamping can thereby also be controlled. Thus, in this simple structure,both the stiffness and damping can be controlled to optimize the seatfor a particular driver. Naturally, if the driver does not like thesettings made by control circuit 150, he or she can change them toprovide a stiffer or softer ride.

[0198] The stiffness of a seat is the change in force divided by thechange in deflection. This is important for many reasons, one of whichis that it controls the natural vibration frequency of the seat occupantcombination. It is important that this be different from the frequencyof vibrations which are transmitted to the seat from the vehicle inorder to minimize the up and down motions of the occupant. The dampingis a force which opposes the motion of the occupant and which isdependent on the velocity of relative motion between the occupant andthe seat bottom. It thus removes energy and minimizes the oscillatorymotion of the occupant. These factors are especially important in truckswhere the vibratory motions of the driver's seat, and thus the driver,have caused many serious back injuries among truck drivers.

[0199] In FIG. 12, the airbag or bladder 515 which interacts with theoccupant is shown with a single chamber. Naturally, bladder 515 can becomposed of multiple chambers 515 a, 515 b, 515 c, and 515 d as shown inFIG. 12A. The use of multiple chambers permits the weight distributionof the occupant to be determined if a separate pressure transducer isused in each cell of the bladder. Such a scheme gives the opportunity ofdetermining to some extent the position of the occupant on the seat orat least the position of the center of gravity of the occupant.Naturally, more than four cells could be used.

[0200] In the description above, the air was use as the fluid to fillthe bladder 515. In some cases, especially where damping and naturalfrequency control is not needed, another fluid such as a liquid or jellcould be used to fill the bladder.

[0201] In an automobile, there is an approximately fixed verticaldistance between the optimum location of the occupant's eyes and thelocation of the pedals. The distant from a driver's eyes to his or herfeet, on the other hand, is not the same for all people. An individualdriver now compensates for this discrepancy by moving the seat and bychanging the angle between his or hers legs and body. For both small andlarge drivers, this discrepancy cannot be fully compensated for and as aresult, their eyes are not appropriately placed. A similar problemexists with the steering wheel. To help correct these problems, thepedals and steering column should be movable as illustrated in FIG. 13which is a plan view similar to that of FIG. 10 showing a driver anddriver seat with an automatically adjustable steering column and pedalsystem which is adjusted based on the morphology of the driver. In FIG.13, a motor 650 is connected to and controls the position of thesteering column and another motor 660 is connected to and controls theposition of the pedals. Both motors 650,660 are coupled to andcontrolled by control circuit 150 wherein now the basic table ofsettings includes values for both the pedals and steering columnlocations.

[0202] As various parts of the vehicle interior identification andmonitoring system described in the above reference patent applicationsare implemented, a variety of transmitting and receiving transducerswill be present in the vehicle passenger compartment. If several ofthese transducers are ultrasonic transmitters and receivers, they can beoperated in a phased array manner, as described above for the headrest,to permit precise distance measurements and mapping of the components ofthe passenger compartment. This is illustrated in FIG. 14 which is aperspective view of the interior of the passenger compartment showing avariety of transmitters and receivers, 700-706 which can be used in aphased array system. In addition, information can be transmitted betweenthe transducers using coded signals in a ultrasonic network through thevehicle compartment airspace. If one of these sensors is an optical CCDor CMOS array, the location of the driver's eyes can be accuratelydetermined and the results sent to the seat ultrasonically. Obviously,many other possibilities exist.

[0203] The eye ellipse discussed above is illustrated at 810 in FIG. 15,which is a view similar to FIG. 1, showing the occupant's eyes and theseat adjusted to place the eyes at a particular vertical position forproper viewing through the windshield and rear view mirror. Many systemsare now under development to improve vehicle safety and driving ease.For example, right vision systems are being tested which project anenhanced image of the road ahead of the vehicle onto the windshield in a“heads-up display”. The main problem with the systems now being testedis that the projected image does not precisely overlap the image as seenthrough the windshield. This parallax causes confusion in the driver andcan only be corrected if the location of the driver's eyes is accuratelyknown. One method of solving this problem is to use the passive seatadjustment system described herein to place the occupant's eyes at theoptimum location as described above. Once this has been accomplished, inaddition to solving the parallax problem, the eyes are properly locatedwith respect to the rear view mirror 820 and little if any adjustment isrequired in order for the driver to have the proper view of what isbehind the vehicle.

[0204] Several systems are in development for determining the locationof an occupant and modifying the deployment of the airbag based of hisor her position. These systems are called “smart airbags”. The passiveseat control system in accordance with this invention can also be usedfor this purpose as illustrated in FIG. 16. This figure is a viewsimilar to FIG. 8 showing an inflated airbag 900 and an arrangement forcontrolling both the flow of gas into and out of the airbag during acrash. The determination is made based on height sensors 120, 121 and122 located in the headrest, a weight sensor 200 in the seat and thelocation of the seat which is known by control circuit 150 (See, FIGS.8, 9 and 9A). Other smart airbags systems rely only on the position ofthe occupant determined from various position sensors using ultrasonicsor optical sensors.

[0205] The weight sensor coupled with the height sensor and theoccupant's velocity relative to the vehicle, as determined by theoccupant position sensors, provides information as to the amount ofenergy which the airbag will need to absorb during the impact of theoccupant with the airbag. This, along with the location of the occupantrelative to the airbag, is then used to determine the amount of gaswhich is to be injected into the airbag during deployment and the sizeof the exit orifices which control the rate of energy dissipation as theoccupant is interacting with the airbag during the crash. For example,if an occupant is particularly heavy then it is desirable to increasethe amount of gas, and thus the initial pressure, in the airbag toaccommodate the larger force which will be required to arrest therelative motion of the occupant. Also, the size of the exit orificesshould be reduced, since there will be a larger pressure tending toforce the gas out of the orifices, in order to prevent the bag frombottoming out before the occupant's relative velocity is arrested.Similarly, for a small occupant the initial pressure would be reducedand the size of the exit orifices increased. If, on the other hand, theoccupant is already close to the airbag then the amount of gas injectedinto the airbag needs to be reduced.

[0206] There are many ways of varying the amount of gas injected intothe airbag some of which are covered in the patent literature andinclude, for example, inflators where the amount of gas generated andthe rate of generation is controllable. For example, in a particularhybrid inflator manufactured by the Allied Signal Corporation (now BreedTechnologies), two pyrotechnic charges are available to heat the storedgas in the inflator. Either or both of the pyrotechnic charges can beignited and the timing between the ignitions can be controlled tosignificantly vary the rate of gas flow to the airbag.

[0207] The flow of gas out of the airbag is traditionally done throughfixed diameter orifices placed in the bag fabric. Some attempts havebeen made to provide a measure of control through such measures asblowout patches applied to the exterior of the airbag. Other systemswere disclosed in U.S. patent application Ser. No. 07/541,464 filed Feb.9, 1989, now abandoned. FIG. 16A illustrates schematically an inflator910 generating gas to fill airbag 900 through control valve 920. Theflow of gas out of airbag 900 is controlled by exit control valve 930.The valve 930 can be implemented in many different ways including, forexample, a motor operated valve located adjacent the inflator and influid communication with the airbag or a digital flow control valve asdiscussed above. When control circuit 150 determines the size and weightof the occupant, the seat position and the relative velocity of theoccupant, it then determines the appropriate opening for the exit valve930, which is coupled to the control circuit 150. A signal is then sentfrom control circuit 150 to the motor controlling this valve whichprovides the proper opening.

[0208] In a like manner, other parameters can also be adjusted, such asthe direction of the airbag, by properly positioning the angle andlocation of the steering wheel relative to the driver. If seatbeltpretensioners are used, the amount of tension in the seatbelt or theforce at which the seatbelt spools out, for the case of force limiters,could also be adjusted based on the occupant morphologicalcharacteristics determined by the system of this invention.

[0209] Once the morphology of the driver and the seat position is known,many other objects in the vehicle can be automatically adjusted toconform to the occupant. An automatically adjustable seat armrest, a cupholder, the cellular phone, directional microphone, visor or any otherobjects with which the driver interacts can be now moved to accommodatethe driver. This is in addition to the personal preference items such asthe radio station, temperature, etc. discussed above.

[0210] Once the system of this invention is implemented, additionalfeatures become possible such as a seat which automatically makes slightadjustments to help alleviate fatigue or to account for a change ofposition of the driver in the seat, or a seat which automaticallychanges position slightly based on the time of day. Many people preferto sit more upright when driving at night, for example. Other similarimprovements based on knowledge of the occupant morphology will nowbecome obvious to those skilled in the art.

[0211] In the above-described component adjustment systems and methods,one of the characteristics of the occupying item that may be measured isthe weight. Several non-limiting examples of weight measuring apparatuswill now be described which may be used in the above-described systemsand methods.

[0212] In a first embodiment of a weight measuring apparatus shown inFIG. 18, four strain gage weight sensors or transducers are used, twobeing illustrated at 1010 and 1011 on one side of a bracket of thesupport structure of the seat and the other two being at the samelocations on another bracket of the support (i.e., hidden on thecorresponding locations on the other side of the support). The supportstructure of the seat supports the seat on a substrate such as a floorpan of the vehicle. Each of the strain gage transducers 1010,1011 alsocontains electronic signal conditioning apparatus, e.g., amplifiers,analog to digital converters, filters etc., which is associated suchthat output from the transducers is a digital signal. This electronicsignal travels from transducer 1010 to transducer 1011 through a wire1020. Similarly, wire 1021 transmits the output from transducers 1010and 1011 to the next transducer in the sequence (one of the hiddentransducers). Additionally, wire 1022 carries the output from thesethree transducers toward the fourth transducer (the other hiddentransducer) and wire 1023 finally carries all four digital signals to anelectronic control system or module 1030. These signals from thetransducers 1010,1011 are time or frequency division multiplexed as iswell known in the art. The seat position is controlled by motors 1040 asdescribed in detail in U.S. Pat. No. 5,179,576, which is incorporatedherein by reference. Finally, the seat is bolted onto the supportstructure through bolts not shown which attach the seat through holes1050 in the brackets.

[0213] By placing the signal conditioning electronics, analog to digitalconverters, and other appropriate electronic circuitry adjacent thestrain gage element, the four transducers can be daisy chained orotherwise attach together and only a single wire is required to connectall of the transducers to the control module 1030 as well as provide thepower to run the transducers and their associated electronics.

[0214] The control system 1030, e.g., a microprocessor, is arranged toreceive the digital signals from the transducers 1010,1011 and determinethe weight of the occupying item of the seat based thereon. In otherwords, the signals from the transducers 1010,1011 are processed by thecontrol system 1030 to provide an indication of the weight of theoccupying item of the seat, i.e., the force exerted by the occupyingitem on the seat support structure.

[0215] A typical manually controlled seat structure is illustrated inFIG. 19 and described in greater detail in U.S. Pat. No. 4,285,545. Theseat 1056 (only the frame of which is shown) is attached to a pair ofslide mechanisms 1058 in the rear thereof through support members suchas rectangular tubular structures 1060 angled between the seat 1056 andthe slide mechanisms 1058. The front of the seat 1056 is attached to thevehicle (more particularly to the floor pan) through another supportmember such as a slide member 1062, which is engaged with a housing1064. Slide mechanisms 1058, support members 1060, slide member 1062 andhousing 1064 constitute the support structure for mounting the seat on asubstrate, i.e., the floor pan. Strain gage transducers are located forthis implementation at 1065 and 1066, strain gage transducer 1065 beingmounted on each tubular structure 1060 (only one of which is shown) andstrain gage transducer 1066 being mounted on slide member 1062. When anoccupying item is situated on the seat cushion (not shown), each of thesupport members 1060 and 1062 are deformed or strained. This strain ismeasured by transducers 1065 and 1066, respectively, to enable adetermination of the weight of the item occupying the seat. Morespecifically, a control system or module or other compatible processingunit (not shown) is coupled to the strain gage transducers 1065,1066,e.g., via electrical wires (not shown), to receive the measured strainand utilize the measured strain to determine the weight of the occupyingitem of the seat. The determined weight, or the raw measured strain, maybe used to control a vehicular component such as the airbag.

[0216] Support members 1060 are substantially vertically oriented andare preferably made of a sufficiently rigid, non-bending component.

[0217]FIG. 19A illustrates an alternate arrangement for the seat supportstructures wherein a gusset 1068 has been added to bridge the angle onthe support member 1060. Strain gage transducer 1069 is placed on thisgusset 1068. Since the gusset 1068 is not a supporting member, it can bemade considerably thinner than the seat support member 1060. As the seatis loaded by an occupying item, the seat support member 1060 will bend.Since the gusset 1068 is relatively weak, greater strain will occur inthe gusset 1068 than in the support member 1060. The existence of thisgreater strain permits more efficient use of the strain gage dynamicrange thus improving the accuracy of the weight measurement.

[0218]FIG. 19B illustrates a seat transverse support member 1070 of theseat shown in FIG. 19, which is situated below the base cushion andextends between opposed lateral sides of the seat. This support member1070 will be directly loaded by the vehicle seat and thus will providean average measurement of the force exerted or weight of the occupyingitem. The deflection or strain in support member 1070 is measured by astrain gage transducer 1072 mounted on the support member 1070 for thispurpose. In some applications, the support member 1070 will occupy theentire space fore and aft below the seat cushion. Here it is shown as arelatively narrow member. The strain gage transducer 1072 is coupled,e.g., via an electrical wire (not shown), to a control module or otherprocessing unit (not shown) which utilizes the measured strain todetermine the weight of the occupying item of the seat.

[0219] In FIG. 19, the support members 1060 are shown as rectangulartubes having an end connected to the seat 1056 and an opposite endconnected to the slide mechanisms 1058. In the constructions shown inFIGS. 20A-20C, the rectangular tubular structure has been replaced by acircular tube where only the lower portion of the support isillustrated. FIGS. 20A-20C show three alternate ways of improving theaccuracy of the strain gage system, i.e., the accuracy of themeasurements of strain by the strain gage transducers. Generally, areduction in the stiffness of the support member to which the straingage transducer is mounted will concentrate the force and therebyimprove the strain measurement. There are several means disclosed belowto reduce the stiffness of the support member. These means are notexclusive and other ways to reduce the stiffness of the support memberare included in the invention and the interpretation of the claims.

[0220] In each illustrated embodiment, the transducer is represented by1065 and the substantially vertically oriented support membercorresponding to support member 1060 in FIG. 19 has been labeled 1060A.In FIG. 20A, the tube support member 1060A has been cut to thereby formtwo separate tubes having longitudinally opposed ends and an additionaltube section 1074 is connected, e.g., by welding, to end portions of thetwo tubes. In this manner, a more accurate tube section 1074 can be usedto permit a more accurate measurement of the strain by transducer 1065,which is mounted on tube section 1074.

[0221] In FIG. 20B, a small circumferential cut has been made in tubesupport member 1060A so that a region having a smaller circumferencethan a remaining portion of the tube support member 1060A is formed.This cut is used to control the diameter of the tube support member1060A at the location where strain gage transducer 1065 is measuring thestrain. In other words, the strain gage transducer 1065 is placed at aportion wherein the diameter thereof is less than the diameter ofremaining portions of the tube support member 1060A. The purpose of thiscut is to correct for manufacturing variations in the diameter of thetube support member 1060A. The magnitude of the cut is selected so as tonot significantly weaken the structural member but instead to controlthe diameter tolerance on the tube so that the strain from one vehicleto another will be the same for a particular loading of the seat.

[0222] In FIG. 20C, a small hole 1078 is made in the tube support member1060A adjacent the transducer 1065 to compensate for manufacturingtolerances on the tube support member 1060A.

[0223] From this discussion, it can be seen that all three techniqueshave as their primary purpose to provide increase the accuracy of thestrain in the support member corresponding to weight on the vehicleseat. Naturally, the preferred approach would be to control themanufacturing tolerances on the support structure tubing so that thevariation from vehicle to vehicle is minimized. For some applicationswhere accurate measurements of weight are desired, the seat structurewill be designed to optimize the ability to measure the strain in thesupport members and thereby to optimize the measurement of the weight ofthe occupying item. The inventions disclosed herein, therefore, areintended to cover the entire seat when the design of the seat is such asto be optimized for the purpose of strain gage weight sensing andalternately for the seat structure when it is so optimized.

[0224] Although strain measurement devices have been discussed above,pressure measurement systems can also be used in the seat supportstructure to measure the weight on the seat. Such a system isillustrated in FIG. 21. A general description of the operation of thisapparatus is disclosed in U.S. Pat. No. 5,785,291, which is incorporatedherein by reference. In that patent, the vehicle seat is attached to theslide mechanism by means of bolts 1084. Between the seat and the slidemechanism, a shock-absorbing washer has been used for each bolt. In thepresent invention, this shock-absorbing washer has been replaced by asandwich construction consisting of two washers of shock absorbingmaterial 1080 with a pressure sensitive material 1082 sandwiched inbetween. A variety of materials can be used for the pressure sensitivematerial 1082, which generally work on either the capacitance orresistive change of the material as it is compressed. The wires fromthis material leading to the electronic control system are not shown inthis view. The pressure sensitive material is coupled to the controlsystem, e.g., a microprocessor, and provides the control system with anindication of the pressure applied by the seat on the slide mechanismwhich is related to the weight of the occupying item of the seat.Generally, material 1082 is constructed with electrodes on the opposingfaces such that as the material is compressed, the spacing between theelectrodes is decreased. This spacing change thereby changes both theresistive and the capacitance of the sandwich which can be measured andwhich is a function of the compressive force on the material.Measurement of the change in capacitance of the sandwich, i.e., twospaced apart conductive members, is obtained by any method known tothose skilled in the art, e.g., connecting the electrodes in a circuitwith a source of alternating or direct current. The conductive membersmay be made of a metal. The use of such a pressure sensor is not limitedto the illustrated embodiment wherein the shock absorbing material 1080and pressure sensitive material 1082 are placed around bolt 1084. It isalso not limited to the use or incorporation of shock absorbing materialin the implementation.

[0225]FIG. 21A shows a substitute construction for the bolt 1084 in FIG.21 and which construction is preferably arranged in connection with theseat and the adjustment slide mechanism or between the slide mechanismand the floor. A bolt-like member, hereinafter referred to as a stud400, is threaded 402 on both ends with a portion remaining unthreadedbetween the ends. A SAW strain measuring device including a SAW straingage 404 and antenna 406 is arranged on the center unthreaded section ofthe stud 400 and the stud 400 is attached at its ends to the seat andthe slide mechanism using appropriate threaded nuts. Based on theparticular geometry of the SAW device used, the stud 400 can result inas little as a 3 mm upward displacement of the seat compared to a normalbolt mounting system. No wires are required to attach the SAW device tothe stud 400. The total length of stud 400 may be as little as 1 inch.In operation, an interrogator 408 transmits a radio frequency pulse atfor example, 925 MHz which excites the antenna 406 associated with theSAW strain gage 404. After a delay caused by the time required for thewave to travel the length of the SAW device, a modified wave isre-transmitted to the interrogator 408 providing an indication of thestrain and thus a representative value of the weight of an objectoccupying the seat. For a seat which is normally bolted to the slidemechanism with four bolts, at least four SAW strain measuring devices orsensors would be used. Each conventional bolt could thus be replaced bya stud as described above. Naturally, since the individual SAW devicesare very small, multiple such devices can be placed on the stud toprovide multiple redundant measurements or to permit the stud to bearbitrarily located with at least one SAW device always within directview of the interrogator antenna.

[0226] To avoid potential problems with electromagnetic interference,the stud 400 may be made of a non-metallic, possibly composite, materialwhich would not likely cause or contribute to any possibleelectromagnetic wave interference. The stud 400 could also be modifiedfor use as an antenna.

[0227] If the seat is unoccupied then the frequency of interrogation canbe substantially reduced in comparison to when the seat is occupied. Foran occupied seat, information as to the identity and/or category andposition of an occupying item of the seat can be obtained through theuse of multiple weight sensors. For this reason, and due to the factthat during pre-crash event the position of an occupying item of theseat may be changing rapidly, interrogations as frequently as once every10 milliseconds or even faster can be desirable. This would also enablea distribution of the weight being applied to the seat being obtainedwhich provides an estimation of the position of the object occupying theseat. Using pattern recognition technology, e.g., a trained neuralnetwork, sensor fusion, fuzzy logic, etc., the identification of theobject can be ascertained based on the determined weight and/ordetermined weight distribution.

[0228] Although each of the SAW devices can be interrogated and/orpowered using wireless means, in some cases, it may be desirable tosupply power to and or obtained information from such devices usingwires.

[0229] In FIG. 22, which is a view of a seat attachment structuredescribed in U.S. Pat. No. 5,531,503, where a more conventional straingage load cell design designated 1100 is utilized. One such load celldesign 1100 is illustrated in detail in FIG. 22A.

[0230] A cantilevered beam load cell design using a half bridge straingage system 1110 is shown in FIG. 22A. Fixed resistors mounted withinthe electronic package, which is not shown in this drawing, provide theremainder of the whetstone bridge system. The half bridge system isfrequently used for economic reasons and where some sacrifice inaccuracy is permissible. The load cell 110 includes a member on whichthe strain gage 1110 is situated. The strain gage 1100 includesstrain-measuring elements 1112 and 1114 arranged on the load cell. Thelongitudinal element 1112 measures the tensile strain in the beam whenit is loaded by the seat and its contents, not shown, which is attachedto end 1122 of bolt 1120. The load cell is mounted to the vehicle orother substrate using bolt 1130. Temperature compensation is achieved inthis system since the resistance change in strain elements 1112 and 1114will vary the same amount with temperature and thus the voltage acrossthe portions of the half bridge will remain the same. The strain gage1100 is coupled to a control system (e.g., a microprocessor-not shown)via wires 1124 and receives the measured tensile strain and determinesthe weight of an occupying item of the seat based thereon.

[0231] One problem with using a cantilevered load cell is that itimparts a torque to the member on which it is mounted. One preferredmounting member on an automobile is the floor-pan which will supportsignificant vertical loads but is poor at resisting torques sincefloor-pans are typically about 1 mm (0.04 inches) thick. This problemcan be overcome through the use of a simply supported load cell designdesignated 1200 as shown in FIG. 22B.

[0232] In FIG. 22B, a full bridge strain gage system 1210 is used withall four elements 1212,1214 mounted on the top of a beam 1205. Elements1212 are mounted parallel to the beam 1205 and elements 1214 are mountedperpendicular to it. Since the maximum strain is in the middle of thebeam 1205, strain gage 1210 is mounted close to that location. The loadcell, shown generally as 1200, is supported by the floor pan, not shown,at supports 1230 that are formed by bending the beam 1205 downward atits ends. Fasteners 1220 fit through holes 1222 in the beam 1205 andserve to hold the load cell 1200 to the floor pan without puttingsignificant forces on the load cell 1200. Holes are provided in thefloor-pan for bolt 1240 and for fasteners 1220. Bolt 1240 is attached tothe load cell 1200 through hole 1250 of the beam 1205 which serves totransfer the force from the seat to the load cell 1200. Although thisdesign would place the load cell between the slide mechanism and thefloor, in many applications it would be placed between the seat and theslide mechanism. In the first case, the evaluation algorithm may alsorequire a seat position input if the weight distribution is to bedetermined.

[0233] The electronics package can be potted within hole 1262 usingurethane potting compound 1244 and includes signal conditioningcircuits, a microprocessor with integral ADCs 1280 and a flex circuit1275 (FIG. 22C). The flex circuit 1275 terminates at an electricalconnector 1290 for connection to other vehicle electronics, e.g., acontrol system. The beam 1205 is slightly tapered at location 1232 sothat the strain is constant in the strain gage.

[0234] Although thus far only beam type load cells have been described,other geometries can also be used. One such geometry is a tubular typeload cell. Such a tubular load cell is shown generally at 1300 in FIG.22D and instead of an elongate beam, it includes a tube. It alsocomprises a plurality of strain sensing elements 1310 for measuringtensile and compressive strains in the tube as well as other elements,not shown, which are placed perpendicular to the elements 1310 toprovide for temperature compensation. Temperature compensation isachieved in this manner, as is well known to those skilled in the art ofthe use of strain gages in conjunction with a whetstone bridge circuit,since temperature changes will affect each of the strain gage elementsidentically and the total effect thus cancels out in the circuit. Thesame bolt 1340 can be used in this case for mounting the load cell tothe floor-pan or slide mechanism and for attaching the seat or slidemechanism respectively to the load cell.

[0235] Another alternate load cell design shown generally in FIG. 22E as1400 makes use of a torsion bar 1410 and appropriately placed torsionalstrain sensing elements 1420. A torque is imparted to the bar 1410 bymeans of lever 1430 and bolt 1440 which attaches to the seat structurenot shown. Bolts 1450 attach the mounting blocks 1460 at ends of thetorsion bar 1410 to the vehicle floor-pan.

[0236] The load cells illustrated above are all preferably of the foilstrain gage type. Other types of strain gages exist which would workequally which include wire strain gages and strain gages made fromsilicon. Silicon strain gages have the advantage of having a much largergage factor and the disadvantage of greater temperature effects. For thehigh-volume implementation of this invention, silicon strain gages havean advantage in that the electronic circuitry (signal conditioning,ADCs, etc.) can be integrated with the strain gage for a low costpackage. Other strain gage materials and load cell designs may, ofcourse, be incorporated within the teachings of this invention.

[0237] In particular, a surface acoustical wave (SAW) strain gage can beused in place of conventional wire, foil or silicon strain gages and thestrain measured either wirelessly or by a wire connection. For SAWstrain gages, the electronic signal conditioning can be associateddirectly with the gage or remotely in an electronic control module asdesired. For SAW strain gages, the problems discussed above with lowsignal levels requiring bridge structures and the methods fortemperature compensation may not apply. Generally, SAW strain gages aremore accurate that other technologies but may require a separate sensorto measure the temperature for temperature compensation depending on thematerial used. Materials that can be considered for SAW strain gages arequartz, lithium niobate, lead zirconate, lead titenate, zinc oxide,polyvinylidene fluoride and other piezoelectric materials.

[0238] Many seat designs have four attachment points for the seatstructure to attach to the vehicle. Since the plane of attachment isdetermined by three points, the potential exists for a significantuncertainty or error to be introduced. This problem can be compounded bythe method of attachment of the seat to the vehicle. Some attachmentmethods using bolts, for example, can introduce significant strain inthe seat supporting structure. Some compliance therefore must beintroduced into the seat structure to reduce these attachment inducedstresses to a minimum. Too much compliance, on the other hand, cansignificantly weaken the seat structure and thereby potentially cause asafety issue. This problem can be solved by rendering the compliancesection of the seat structure highly nonlinear or significantly limitingthe range of the compliance. One of the support members, for example,can be attached to the top of the seat structure through the use of thepinned joint wherein the angular rotation of the joint is severelylimited. Methods will now be obvious to those skilled in the art toeliminate the attachment induced stress and strain in the structurewhich can cause inaccuracies in the strain measuring system.

[0239] In the examples illustrated above, strain measuring elements havebeen shown at each of the support members. This of course is necessaryif an accurate measurement of the weight of the occupying item of theseat is to be determined. For this case, typically a single value isinputted into the neural network representing weight. Experiments haveshown, however, for the four strain gage transducer system, that most ofthe weight and thus most of the strain occurs in the strain elementsmounted on the rear seat support structural members. In fact, about 85percent of the load is typically carried by the rear supports. Littleaccuracy is lost therefore if the forward strain measuring elements areeliminated. Similarly, for most cases, the two rear mounted supportstrain elements measure approximately the same strain. Thus, theinformation represented by the strain in one rear seat support issufficient to provide a reasonably accurate measurement of the weight ofthe occupying item of the seat.

[0240] If a system consisting of eight transducers is considered, fourultrasonic transducers and four weight transducers, and if costconsiderations require the choice of a smaller total number oftransducers, it is a question of which of the eight transducers shouldbe eliminated. Fortunately, the neural network technology provides atechnique for determining which of the eight transducers is mostimportant, which is next most important, etc. If the six most criticaltransducers are chosen, that is the six transducers which contain themost useful information as determined by the neural network, and aneural network can be trained using data from those six transducers andthe overall accuracy of the system can be determined. Experience hasdetermined, for example, that typically there is almost no loss inaccuracy by eliminating two of the eight transducers, that is two of thestrain gage weight sensors. A slight loss of accuracy occurs when one ofthe ultrasonic transducers is then eliminated.

[0241] This same technique can be used with the additional transducersdescribed above. A transducer space can be determined with perhapstwenty different transducers comprised of ultrasonic, optical,electromagnetic, motion, heartbeat, weight, seat track, seatbelt payout,seatback angle etc. transducers. The neural network can then be used inconjunction with a cost function to determine the cost of systemaccuracy. In this manner, the optimum combination of any system cost andaccuracy level can be determined.

[0242] In many situations where the four strain measuring weight sensorsare applied to the vehicle seat structure, the distribution of theweight among the four strain gage sensors, for example, well verysignificantly depending on the position of the seat in the vehicle andparticularly the fore and aft and secondarily the seatback angleposition. A significant improvement to the accuracy of the strain gageweight sensors, particularly if less than four such sensors are used,can result by using information from a seat track position and/or aseatback angle sensor. In many vehicles, such sensors already exist andtherefore the incorporation of this information results in littleadditional cost to the system and results in significant improvements inthe accuracy of the weight sensors.

[0243] There have been attempts to use seat weight sensors to determinethe load distribution of the occupying item and thereby reach aconclusion about the state of seat occupancy. For example, if a forwardfacing human is out of position, the weight distribution on the seatwill be different than if the occupant is in position. Similarly a rearfacing child seat will have a different weight distribution than aforward facing child seat. This information is useful for determiningthe seated state of the occupying item under static or slowly changingconditions. For example, even when the vehicle is traveling onmoderately rough roads, a long term averaging or filtering technique canbe used to determine the total weight and weight distribution of theoccupying item. Thus, this information can be useful in differentiatingbetween a forward facing and rear facing child seat.

[0244] It is much less useful however for the case of a forward facinghuman or forward facing child seat that becomes out of position during acrash. Panic braking prior to a crash, particularly on a rough roadsurface, will cause dramatic fluctuations in the output of the weightsensing elements. Filtering algorithms, which require a significant timeslice of data, will also not be particularly useful. A neural network orother pattern recognition system, however, can be trained to recognizesuch situations and provide useful information to improve systemaccuracy.

[0245] Other dynamical techniques can also provide useful informationespecially if combined with data from various vehicle accelerometers. Bystudying the average weight over a few cycles, as measured by eachtransducer independently, a determination can be made that the weightdistribution is changing. Depending on the magnitude of the change adetermination can be made as to whether the occupant is being restrainedby a seatbelt. It a seatbelt restraint is not being used, the outputfrom the crash accelerometer can be used to accurately project theposition of the occupant during pre crash braking and eventually theimpact itself providing his or her initial position is known.

[0246] In this manner, a weight sensor with provides weight distributioninformation can provide useful information to improve the accuracy ofthe occupant position sensing system for dynamic out of positiondetermination. Naturally, even without the weight sensor information,the use of the vehicle crash sensor data in conjunction with any meansof determining the belted state of the occupant will dramaticallyimprove the dynamic determination of the position of a vehicle occupant.

[0247] It should be mentioned that the adjustment system may be used inconjunction with each vehicle seat. In this case, if a seat isdetermined to be unoccupied, then the processor means may be designed toadjust the seat for the benefit of other occupants, i.e., if a frontpassenger side seat is unoccupied but the rear passenger side seat isoccupied, then adjustment system might adjust the front seat for thebenefit of the rear-seated passenger, e.g., move the seat base forward.

[0248]FIG. 23 illustrates the placement of a variety of sensors,primarily accelerometers and/or gyroscopes, which can be used todiagnose the state of the vehicle itself. Sensor 1501 can measure theacceleration of the firewall or instrument panel and is located thereongenerally midway between the two sides of the vehicle. Sensor 1502 canbe located in the headliner or attached to the vehicle roof above theside door. Typically, there will be two such sensors one on either sideof the vehicle. Sensor 1503 is shown in a typical mounting locationmidway between the sides of the vehicle attached to or near the vehicleroof above the rear window. Sensor 1506 is shown in a typical mountinglocation in the vehicle trunk adjacent the rear of the vehicle. One, twoor three such sensors can be used depending on the application. If threesuch sensors are use one would be adjacent each side of vehicle and onein the center. Sensor 1504 is shown in a typical mounting location inthe vehicle door and sensor 1505 is shown in a typical mounting locationon the sill or floor below the door. Finally, sensor 1507, which can bealso multiple sensors, is shown in a typical mounting location forwardin the crush zone of the vehicle. If three such sensors are used, onewould be adjacent each vehicle side and one in the center. Additionally,sensor 1508 can be mounted on the floor or base of the seat structure tomeasure the seat base acceleration or “forcing function” on the seat.

[0249] In general, sensors 1501-1508 measure a physical property of thelocation at which they are mounted. For example, the physical propertywould be the acceleration of the mounting location if the sensor is anaccelerometer and would be angular inclination if the sensor is agyroscope. Another way of looking at would be to consider that sensors1501-1508 provide a measurement of the state of the sensor, such as itsvelocity, acceleration, angular orientation or temperature, or a stateof the location at which the sensor is mounted. Thus, measurementsrelated to the state of the sensor would include measurements of theacceleration of the sensor, measurements of the temperature of themounting location as well as changes in the state of the sensor andrates of changes of the state of the sensor. However, any described useor function of the sensors 1501-1508 above is merely exemplary and isnot intended to limit the form of the sensor or its function.

[0250] Each of the sensors 1501-1508 may be single axis, double axis ortriaxial accelerometers and/or gyroscopes typically of the MEMS type.These sensors 1501-1508 can either be wired to the central controlmodule or processor directly wherein they would receive power andtransmit information, or they could be connected onto the vehicle busor, in some cases, using RFID or SAW technology, the sensors can bewireless and would receive their power through RF from one or moreinterrogators located in the vehicle. In this case, the interrogatorscan be connected either to the vehicle bus or directly to controlmodule. Alternately, an inductive or capacitive power and informationtransfer system can be used.

[0251] One particular implementation will now be described. In thiscase, each of the sensors 1501-1508 is a single or dual axisaccelerometer. They are made using silicon micromachined technology suchas disclosed in U.S. Pat. Nos. 5,121,180 and 5,894,090. These are onlyrepresentative patents of these devices and there exist more than 100other relevant U.S. patents describing this technology. Commerciallyavailable MEMS gyroscopes such as from Systron Doner have accuracies ofapproximately one degree per second. In contrast, optical gyroscopestypically have accuracies of approximately one degree per hour.Unfortunately, the optical gyroscopes are prohibitively expensive forautomotive applications. On the other hand, typical MEMS gyroscopes arenot sufficiently accurate for many control applications.

[0252] The angular rate function can be obtained through placingaccelerometers at two separated, non-co-located points in a vehicle andusing the differential acceleration to obtain an indication of angularmotion and angular acceleration. From the variety of accelerometersshown on FIG. 23, it can be readily appreciated that not only will allaccelerations of key parts of the vehicle be determined, but the pitch,yaw and roll angular rates can also be determined based on the accuracyof the accelerometers. By this method, low cost systems can be developedwhich, although not as accurate as the optical gyroscopes, areconsiderably more accurate than conventional MEMS gyroscopes.

[0253] Instead of using two accelerometers at separate locations on thevehicle, a single conformal MEMS-IDT gyroscope may be used. Such aconformal MEMS-IDT gyroscope is described in a paper by V. K. Karadan,“Conformal MEMS-IDT Gyroscopes and Their Comparison With Fiber OpticGyro”, incorporated in its entirety herein. The MEMS-IDT gyroscope isbased on the principle of surface acoustic wave (SAW) standing waves ona piezoelectric substrate. A surface acoustic wave resonator is used tocreate standing waves inside a cavity and the particles at theanti-nodes of the standing waves experience large amplitude ofvibrations, which serves as the reference vibrating motion for thegyroscope. Arrays of metallic dots are positioned at the anti-nodelocations so that the effect of Coriolis force due to rotation willacoustically amplify the magnitude of the waves. Unlike other MEMSgyroscopes, the MEMS-IDT gyroscope has a planar configuration with nosuspended resonating mechanical structures.

[0254] The system of FIG. 23 using dual axis accelerometers, thereforeprovide a complete diagnostic system of the vehicle itself and itsdynamic motion. Such a system is far more accurate than any systemcurrently available in the automotive market. This system provides veryaccurate crash discrimination since the exact location of the crash canbe determined and, coupled with a knowledge of the force deflectioncharacteristics of the vehicle at the accident impact site, an accuratedetermination of the crash severity and thus the need for occupantrestraint deployment can be made. Similarly, the tendency of a vehicleto roll over can be predicted in advance and signals sent to the vehiclesteering, braking and throttle systems to attempt to ameliorate therollover situation or prevent it. In the event that it cannot beprevented, the deployment side curtain airbags can be initiated in atimely manner.

[0255] Similarly, the tendency of the vehicle to the slide or skid canbe considerably more accurately determined and again the steering,braking and throttle systems commanded to minimize the unstable vehiclebehavior.

[0256] Thus, through the sample deployment of inexpensive accelerometersand MEMS gyroscopes, particularly MEMS-IDT gyroscopes, at a variety oflocations in the vehicle, significant improvements are many in thevehicle stability control, crash sensing, rollover sensing, andresulting occupant protection technologies.

[0257] Finally, as mentioned above, the combination of the outputs fromthese accelerometer sensors and the output of strain gage or bladderweight sensors in a vehicle seat, or in or on a support structure of theseat, can be used to make an accurate assessment of the occupancy of theseat and differentiate between animate and inanimate occupants as wellas determining where in the seat the occupants are sitting and the stateof the seatbelt use.

[0258] This can be done by observing the acceleration signals from thesensors (accelerometers) of FIG. 23 and simultaneously measuring,detecting or determining the dynamic strain or pressure gagemeasurements from the seat-mounted strain or pressure gages. Theaccelerometers provide the input function to the seat and the strain orpressure gages measure the reaction of the occupying item to the vehicleacceleration and thereby provide a method for determining dynamicallythe mass and other inertial properties of the occupying item and itslocation and seatbelt usage. This is particularly important duringoccupant position sensing during a crash event.

[0259] By combining the outputs of the accelerometers and the strain orpressure gages and appropriately processing the same, the mass andweight of an object occupying the seat can be determined as well as thegross motion of such an object so that an assessment can be made as towhether the object is a life form such as a human being.

[0260] Several ways to process the acceleration signal and the stain orpressure signal are discussed below with reference to FIG. 24. Ingeneral, the dynamic load applied to the seat is measured or a forcingfunction of the seat is measured, as a function of the accelerationsignal. This represents the effect of the movement of the vehicle on theoccupant which is reflected in the measurement of weight by the strainor pressure gages. Thus, the measurement obtained by the strain orpressure gages can be considered to have two components, one componentresulting from the weight applied by the occupant in a stationary stateof the vehicle and the other arising or resulting from the movement ofthe vehicle. The vehicle-movement component can be separated from thetotal strain or pressure gage measurement to provide a more accurateindication of the weight of the occupant.

[0261] For this embodiment, sensor 1509 represents one or more strain orbladder pressure gage weight sensors mounted on the seat or inconnection with the seat or its support structure. Suitable mountinglocations and forms of weight sensors are discussed in the currentassignee's U.S. Pat. No. 6,242,701 and contemplated for use in thisinvention as well. The mass or weight of the occupying item of the seatcan thus be measured based on the dynamic measurement of the straingages with optional consideration of the measurements of accelerometerson the vehicle, which are represented by any of sensors 1501-1508.

[0262] To provide a feeling for the implementation of this invention,consider the following approximate analysis.

[0263] To begin with, the seatbelt is a one-way spring in that the forceis high for upward motion and low for downward motion. This howeverintroduces non-linearity into the analysis making an exact solutiondifficult. Therefore for the purposes of this simplified analysis, anassumption is made that the force from the seatbelt is the same in bothdirections. Although the stiffness of the seat will vary significantlyfrom vehicle to vehicle, assume here that it is about 30 kg per cm. Alsoassume that the input from the road is 1 Hz with a magnitude of 10 cmfor the vertical motion of the vehicle wheels (axel) on the road. Themotion of the seat will be much less due to the vehicle suspensionsystem.

[0264] The problem is to find is the weight of an occupant from theresponse of the seat (as measured by strain or pressure gages) to theroad displacement acting through the vehicle suspension. The intent hereis only to show that it is possible to determine the weight of theoccupant and the use of a seatbelt by measuring the dynamic strain orpressure due to the seat motion as a function of the weight of theoccupant and the seatbelt force. The functions and equations used belowand the solution to them can be implemented in a processor.

[0265] Looking now at FIG. 24, suppose that point A (the point where aseatbelt is fixed to the seat) and point B are subjected to harmonicdisplacements u(t)=U₀ cos ωt caused by a car's vertical movements on theroad. As a result, springs modeling a seat and a seatbelt (theircorresponding stiffness are k_(s) and k_(sb)) affect a passenger mass mwith forces −k_(sb)(u−x) and k_(s)(u−x). (Minus in the first force istaken because the seatbelt spring contracts when the seat springstretches and vice versa). Under the forces action, the mass getsacceleration d₂x/dt², so the initial equation to be solved will be$\begin{matrix}{{m\frac{^{2}x}{t^{2}}} = {{- {k_{sb}( {u - x} )}} + {{k_{s}( {u - x} )}.}}} & (1)\end{matrix}$

[0266] This equation can be rewritten in the form $\begin{matrix}{{{m\frac{^{2}x}{t^{2}}} + {( {k_{s} - k_{sb}} )x}} = {{u(t)}{( {k_{s} - k_{sb}} ).{or}}}} & (2) \\{{{m\frac{^{2}x}{t^{2}}} + {( {k_{s} - k_{sb}} )x}} = {{U_{0}( {k_{s} - k_{sb}} )}\cos \quad \omega \quad t}} & (3)\end{matrix}$

[0267] This is a differential equation of a harmonic oscillator underaction of a harmonic external force ƒ(t)=U₀(t)(K_(s)−K_(sb)) cos ωt. Ifthere is no seatbelt (k_(sb)−), the solution of this equation in theease of a harmonic external force ƒ(t)−F₀ cos ωt is well known [StrelkovS. P. Introduction in the theory of oscillations, Moscow, “Nauka”, 1964,p. 56]: $\begin{matrix}{{{x(t)} = {{\frac{U_{0}}{( {1 - \frac{\omega^{2}}{\omega_{0}^{2}}} )}\cos \quad \omega \quad t} + {C_{1}\cos \quad \omega_{0}t} + {C_{2}\sin \quad \omega_{0}t}}},} & (4)\end{matrix}$

[0268] where the oscillator natural frequency. $\begin{matrix}{\omega_{0} = {\sqrt{\frac{k_{s}}{m}}.}} & (5)\end{matrix}$

[0269] The second and third terms in equation (4) describe naturaloscillations of the oscillator, which decay if there is any, even verysmall, friction in the system. Having assumed such small friction to bepresent, for steady forced oscillation, the equation is thus:$\begin{matrix}{{x(t)} = {\frac{U_{0}}{1 - \frac{\omega^{2}}{\omega_{0}^{2}}}\cos \quad \omega \quad {t.}}} & (6)\end{matrix}$

[0270] Thus, in steady mode the system oscillates with the externalforce frequency ω. Now, it is possible to calculate acceleration of themass: $\begin{matrix}{{\frac{^{2}x}{t^{2}} = {{- \frac{\omega^{2}U_{0}}{1 - \frac{\omega^{2}}{\omega_{0}^{2}}}}\cos \quad \omega \quad t}},} & (7)\end{matrix}$

[0271] and the amplitude of the force acting in the system$\begin{matrix}{F_{m} = {{{m\frac{^{2}x}{t^{2}}}} = {{{- \frac{m\quad \omega^{2}U_{0}}{1 - \frac{\omega^{2}}{\omega_{0}^{2}}}}}.}}} & (8)\end{matrix}$

[0272] In the situation where a seatbelt is present, it is not possibleto use the same formulae because the seatbelt stiffness is alwaysgreater than stiffness of a seat, and (k_(s)−k_(sb))<0. Therefore,instead of equation (3) we should consider the equation $\begin{matrix}{{{\frac{^{2}x}{t^{2}} - {\omega_{0}^{2}x}} = {{- \omega_{0}^{2}}U_{0}\cos \quad \omega \quad t}},} & (9)\end{matrix}$

[0273] where ω₀² = k_(s) − k_(sb)/m > 0.

[0274] Following the same procedure (Strelkov S. P., ibid.), one canfind a particular solution of inhomogeneous equation (9):$\begin{matrix}{{x(t)} = {\frac{U_{0}}{1 + \frac{\omega^{2}}{\omega_{0}^{2}}}\cos \quad \omega \quad {t.}}} & (10)\end{matrix}$

[0275] Then its general solution will be [as per Korn G. A., Korn T. M.Mathematical handbook for scientists and engineers. Russian translation:Moscow, “Nauka”, 1970, pp. 268-270]: $\begin{matrix}{{x(t)} = {{\frac{U_{0}}{( {1 + \frac{\omega^{2}}{\omega_{0}^{2}}} )}\cos \quad \omega \quad t} + {C_{1}\cos \quad \omega_{0}t} + {C_{2}\sin \quad \omega_{0}{t.}}}} & (11)\end{matrix}$

[0276] Thus, in a steady mode, the amplitude of the acting force is:$\begin{matrix}{{F_{m} = {{- \frac{m\quad \omega^{2}U_{0}}{1 + \frac{\omega^{2}}{\omega_{0}^{2}}}}}},} & (12)\end{matrix}$

[0277] and the natural frequency of the system is: $\begin{matrix}{\omega_{0} = {\sqrt{\frac{{k_{s} - k_{sb}}}{m}}.}} & (13)\end{matrix}$

[0278] Using the formulae (5), (8) (the “no seatbelt case”), (12) and(13) (the “seatbelt present case”), a table can be created as shownbelow. In the table, pm denotes amplitude of pressure acting on the seatsurface. The initial data used in calculations are as follows:

[0279] k_(s)−30 Kg/cm=3×10⁴ N/m (the seat stiffness);

[0280] k_(sb)=600 N/0.3 cm=2×10⁵ N/m (the seatbelt stiffness);

[0281] U₀=0.1 m (the acting displacement amplitude);

[0282] ƒ=1 Hz (the acting frequency).

[0283] S=0.05 m² (the seat surface square that the passenger actingupon).

[0284] Naturally, where the frequency ƒ=ω/2π, ƒ₀ is natural frequency ofthe system. Columns “No seatbelt” is calculated when k_(sb)=0. Thepassenger No seatbelt There is a seatbelt mass, kg f₀, Hz F_(m), Np_(m), Pa f₀, Hz F_(m), N p_(m), Pa 20 6.2 81.1 1.62 × 10³ 14.7 78.61.57 × 10³ 40 4.4 166.7 3.33 × 10³ 10.4 156.5 3.13 × 10³ 60 3.6 257.25.14 × 10³ 8.5 233.6 4.67 × 10³ 100 2.8 454.6 9.09 × 10³ 6.6 385.8 7.72× 10³

[0285] From the above table, it can be seen that there is a differentcombination of seat structure force (as can be measured by straingages), or pressure (as can be measured by a bladder and pressuresensor) and natural frequency for each combination of occupant weightand seatbelt use. Indeed, it can easily be seen that use of a seatbeltsignificantly affects the weight measurement of the weight sensors. Byusing the acceleration data, e.g., a forcing function, it is possible toeliminate the effect of the seatbelt and the road on the weightmeasurement. Thus, by observing the response of the seat plus occupantand knowing the input from the road, an estimate of the occupant weightand seatbelt use can be made without even knowing the static forces orpressures in the strain or pressure gages. By considering the dynamicresponse of the seat to road-induced input vibrations, the occupantweight and seatbelt use can be determined.

[0286] In an actual implementation, the above problem can be solved moreaccurately by using a pattern recognition system that compares thepattern of the seat plus occupant response (pressure or strain gagereadings) to the pattern of input accelerations. This can be donethrough the training of a neural network, modular neural network orother trainable pattern recognition system. Naturally, many othermathematical techniques can be used to solve this problem includingvarious simulation methods where the coefficients of dynamical equationsare estimated from the response of the seat and occupant to the inputacceleration. Thus, although the preferred implementation of the presentinvention is to use neural networks to solve this problem, the inventionis not limited thereby.

[0287] One embodiment of a weight sensor and method for determining theweight of an occupant of a seat, which may be used in the methods andapparatus for adjusting a vehicle component and identifying an occupantof a seat, comprises a bladder having at least one chamber adapted to bearranged in a seat portion of the seat, and at least one transducer formeasuring the pressure in a respective chamber. The bladder maycomprises a plurality of chambers, each adapted to be arranged at adifferent location in the seat portion of the seat. Thus, it is possibleto determine the weight distribution of the occupant using this weightsensor with several transducers whereby each transducer is associatedwith one chamber and the weight distribution of the occupant is obtainedfrom the pressure measurements of the transducers. The position of theoccupant and the center of gravity of the occupant can also bedetermined based on the weight distribution.

[0288] A novel occupant position sensor for a vehicle, for determiningthe position of the occupant, comprises a weight sensor for determiningthe weight of an occupant of a seat as described immediately above andprocessor means for receiving the determined weight of the occupant fromthe weight sensor and determining the position of the occupant based atleast on part on the determined weight of the occupant. The position ofthe occupant could also be determined based in part on waves receivedfrom the space above the seat, data from seat position sensors,reclining angle sensors, etc.

[0289] In an apparatus for adjusting the stiffness of a seat in avehicle, at least two containers are arranged in or near a bottomportion of the seat, the first container substantially supports the loadof a seat occupant and the second container is relatively unaffected bythis load. The two containers are in flow communication with each otherthrough a variable flow passage. Insertion means, e.g., an aircompressor, are provided for directing a medium into one of thecontainer and monitoring means, e.g., a pressure transducer, measuringthe pressure in one or both containers. A control circuit is coupled tothe medium insertion means and the monitoring means for regulating flowof medium into the first container via the medium insertion means untilthe pressure in the first container as measured by the monitoring meansis indicative of a desired stiffness for the seat. The control circuitmay also be arranged to adjust the flow passage to thereby control flowof medium between the two containers and thus damping the motion of onobject on the seat. The flow passage may be an orifice in a peripheralwall of the inner container.

[0290] A method for adjusting the stiffness of a seat in a vehiclecomprises the steps of arranging a first container in a bottom portionof the seat and subjected to the load on the seat, arranging a secondcontainer in a position where it is relatively unaffected by the load onthe seat, coupling interior volumes of the two containers through avariable flow passage, measuring the pressure in the first container,and introducing medium into the first container until the measuredpressure in the first container is indicative of a desired stiffness forthe seat.

[0291] One embodiment of a seated-state detecting unit and method forascertaining the identity of an object in a seat in a passengercompartment of a vehicle in accordance with the invention comprises awave-receiving sensor arranged to receive waves from a space above theseat and generate an output representative of the received waves, weightmeasuring means associated with the seat for measuring the weightapplied onto the seat (such as described above) and generating an outputrepresentative of the measured weight applied onto the seat, andprocessor means for receiving the outputs from the wave-receiving sensorand the weight measuring means and for evaluating the seated-state ofthe seat based thereon to determine whether the seat is occupied by anobject and when the seat is occupied by an object, to ascertain theidentity of the object in the seat based on the outputs from thewave-receiving sensor and the weight measuring means. If necessarydepending on the type of wave-receiving sensor, waves are transmittedinto the passenger compartment toward the seat to enable reception ofthe same by the wave-receiving sensor. The wave-receiving sensor may bean ultrasonic sensor structured and arranged to receive ultrasonicwaves, an electromagnetic sensor structured and arranged to receiveelectromagnetic waves or a capacitive or electric field sensor forgenerating an output representative of the object based on the object'sdielectric properties. The processor means may comprise a microcomputerinto which a function correlating the outputs from the wave-receivingsensor and the weight measuring means and the seated-state of the seatis incorporated or a neural network which generates a functioncorrelating the outputs from the wave-receiving sensor and the weightmeasuring means and the seated-state of the seat and executes thefunction using the outputs from the wave-receiving sensor and the weightmeasuring means as input to determine the seated-state of the seat.

[0292] Additional sensors may be provided to enhance the procedure forascertaining the identity of the object. Such sensors, e.g., a seatposition detecting sensor, reclining angle detecting sensor, heartbeator other animal life state sensor, motion sensor, etc., provide outputdirectly or indirectly related to the object which is considered by theprocessor means when evaluating the seated-state of the seat.

[0293] The weight measuring means may comprise one or more weightsensors such as strain gage bases sensors, possibly arranged inconnection with the seat, for measuring the force or pressure appliedonto at least a portion of the seat. In the alternative, a bladderhaving at least one chamber may be arranged in a seat portion of theseat for measuring the force or pressure applied onto at least a portionof the seat.

[0294] The adjustment system and method for adjusting a component of avehicle based on the presence of an object on a seat include awave-receiving sensor as described immediately above, weight measuringmeans as described above, adjustment means arranged in connection withthe component for adjusting the component, and processor means forreceiving the outputs from the wave-receiving sensor and the weightmeasuring means and for evaluating the seated-state of the seat basedthereon to determine whether the seat is occupied by an object and whenthe seat is occupied by an object, to ascertain the identity of theobject in the seat based on the outputs from the wave-receiving sensorand the weight measuring means. The processor means also direct theadjustment means to adjust the component based at least on the identityof the object.

[0295] If the component is an airbag system, the processor means may bedesigned to direct the adjustment means to suppress deployment of theairbag when the object is identified as an object for which deploymentof the airbag is unnecessary or would be more likely to harm the objectthan protect the object, depowering the deployment of the airbag oraffect any deployment parameter, e.g., the inflation rate, deflationrate, number of deploying airbags, deployment rate, etc. Thus, thecomponent may be a valve for regulating the flow of gas into or out ofan airbag.

[0296] Another embodiment of the apparatus in accordance with inventionincludes a first measuring system for measuring a first morphologicalcharacteristic of the occupying item of the seat and a second measuringsystem for measuring a second morphological characteristic of theoccupying item. Morphological characteristic include the weight of theoccupying item, the height of the occupying item from the bottom portionof the seat and if the occupying item is a human, the arm length, headdiameter, facial features, fingerprint, handprint, voiceprint, irispattern, leg length and dielectric properties. The apparatus alsoincludes processor means for receiving the output of the first andsecond measuring systems and for processing the outputs to evaluate aseated-state based on the outputs. The measuring systems describedherein, as well as any other conventional measuring systems, may be usedin the invention to measure the morphological characteristics of theoccupying item.

[0297] One preferred embodiment of an adjustment system in accordancewith the invention includes a plurality of wave-receiving sensors forreceiving waves from the seat and its contents, if any, and one or moreweight sensors for detecting weight of an occupant in the seat or anabsence of weight applied onto the seat indicative of a vacant seat. Theapparatus also includes processor means for receiving the output of thewave-receiving sensors and the weight sensor(s) and for processing theoutputs to evaluate a seated-state based on the outputs. The processormeans then adjust a part of the component or the component in itsentirety based at least on the evaluation of the seated-state of theseat. The wave-receiving sensors may be ultrasonic sensors, opticalsensors or electromagnetic sensors operating at other than opticalfrequencies. If the wave-receiving sensors are ultrasonic or opticalsensors, then they may also include transmitter means for transmittingultrasonic or optical waves toward the seat. For the purposes herein,optical is used to include the infrared, visible and ultraviolet partsof the electromagnetic spectrum.

[0298] If the component is a seat, the system includes power means formoving at least one portion of the seat relative to the passengercompartment and control means connected to the power means forcontrolling the power means to move the portion(s) of the seat. In thiscase, the processor means may direct the control means to affect thepower means based at least in part on the evaluation of the seated-stateof the seat. With respect to the direction or regulation of the controlmeans by the processor means, this may take the form of a regulationsignal to the control means that no seat adjustment is needed, e.g., ifthe seat is occupied by a bag of groceries or a child seat in a rear orforward-facing position as determined by the evaluation of the outputfrom the ultrasonic or optical and weight sensors. On the other hand, ifthe processor means determines that the seat is occupied by an adult orchild for which adjustment of the seat is beneficial or desired, thenthe processor means may direct the control means to affect the powermeans accordingly. For example, if a child is detected on the seat, theprocessor means may be designed to lower the headrest.

[0299] In certain embodiments, the apparatus may include one or moresensors each of which measures a morphological characteristic of theoccupying item of the seat, e.g., the height, weight or dielectricproperties of the occupying item, and the processor means are arrangedto obtain the input from these sensors and adjust the componentaccordingly. Thus, once the processor means evaluates the occupancy ofthe seat and determines that the occupancy is by an adult or child, thenthe processor means may additionally use either the obtained weightmeasurement or conduct additional measurements of morphologicalcharacteristics of the adult or child occupant and adjust the componentaccordingly. The processor means may be a single microprocessor forperforming all of the functions described above. In the alternative, onemicroprocessor may be used for evaluating the occupancy of the seat andanother for adjusting the component.

[0300] The processor means may comprise an evaluation circuitimplemented in hardware as an electronic circuit or in software as acomputer program or a combination thereof.

[0301] In certain embodiments, a correlation function or state betweenthe output of the various sensors and the desired result (i.e., seatoccupancy identification and categorization) is determined, e.g., by aneural network that may be implemented in hardware as a neural computeror in software as a computer program. The correlation function or statethat is determined by employing this neural network may also becontained in a microcomputer. In this case, the microcomputer can beemployed as an evaluation circuit. The word circuit herein will be usedto mean both an electronic circuit and the functional equivalentimplemented on a microcomputer using software.

[0302] In enhanced embodiments, a heartbeat or animal life state sensormay be provided for detecting the heartbeat of the occupant if presentor animal life state and generating an output representative thereof Theprocessor means additionally receives this output and evaluates theseated-state of the seat based in part thereon. In addition to orinstead of such a heartbeat or animal life state sensor, a capacitive orelectric field sensor and/or a motion sensor may be provided. Thecapacitive sensor is a particular implementation of an electromagneticwave sensor that detects the presence of the occupant and generates anoutput representative of the presence of the occupant based on itsdielectric properties. The motion sensor detects movement of theoccupant and generates an output representative thereof. These outputsare provided to the processor means for possible use in the evaluationof the seated-state of the seat.

[0303] The portion of the apparatus which includes the ultrasonic,optical or non-optical electromagnetic sensors, weight measuring meansand processor means which evaluate the occupancy of the seat based onthe measured weight of the seat and its contents and the returned wavesfrom the ultrasonic, optical or non-optical electromagnetic sensors maybe considered to constitute a seated-state detecting unit.

[0304] The seated-state detecting unit may further comprise a seatposition-detecting sensor. This sensor determines the position of theseat in the forward and aft direction. In this case, the evaluationcircuit evaluates the seated-state, based on a correlation functionobtained from outputs of the ultrasonic sensors, an output of the one ormore weight sensors, and an output of the seat position detectingsensor. With this structure, there is the advantage that theidentification between the flat configuration of a detected surface in astate where a passenger is not sitting in the seat and the flatconfiguration of a detected surface which is detected when a seat isslid backwards by the amount of the thickness of a passenger, that is,of identification of whether a passenger seat is vacant or occupied by apassenger, can be reliably performed.

[0305] Furthermore, the seated-state detecting unit may also comprise aseat back reclining angle detecting sensor, and the evaluation circuitmay also evaluate the seated-state based on a correlation functionobtained from outputs of the ultrasonic, optical or non-opticalelectromagnetic sensors, an output of the weight sensor(s), and anoutput of the seat back reclining angle detecting sensor. In this case,if the tilted angle information of the back portion of the seat is addedas evaluation information for the seated-state, identification can beclearly performed between the flat configuration of a surface detectedwhen a passenger is in a slightly slouching state and the configurationof a surface detected when the back portion of a seat is slightly tiltedforward and similar difficult-to-discriminate cases. This embodiment mayeven be combined with the output from a seat position-detecting sensorto further enhance the evaluation circuit.

[0306] Moreover, the seated-state detecting unit may further comprise acomparison circuit for comparing the output of the weight sensor(s) witha reference value. In this case, the evaluation circuit identifies anadult and a child based on the reference value.

[0307] The seated-state detecting unit may comprise a plurality ofultrasonic, optical or non-optical electromagnetic sensors fortransmitting ultrasonic or electromagnetic waves toward a seat andreceiving reflected waves from the seat; one or more weight sensors fordetecting weight of a passenger in the seat; a seat position detectingsensor; a reclining angle detecting sensor; and a neural network towhich outputs of the ultrasonic or electromagnetic sensors and theweight sensor(s), an output of the seat position detecting sensor, andan output of the reclining angle detecting sensor are inputted and whichevaluates several kinds of seated-states, based on a correlationfunction obtained from the outputs.

[0308] The kinds of seated-states that can be evaluated and categorizedby the neural network include the following categories, among others,(i) a normally seated passenger and a forward facing child seat, (ii) anabnormally seated passenger and a rear-facing child seat, and (iii) avacant seat.

[0309] The seated-state detecting unit may further comprise a comparisoncircuit for comparing the output of the weight sensor(s) with areference value and a gate circuit to which the evaluation signal and acomparison signal from the comparison circuit are input. This gatecircuit, which may be implemented in software or hardware, outputssignals which evaluates several kinds of seated-states. These kinds ofseated-states can include a (i) normally seated passenger, (ii) aforward facing child seat, (iii) an abnormally seated passenger, (iv) arear facing child seat, and (v) a vacant seat. With this arrangement,the identification between a normally seated passenger and a forwardfacing child seat, the identification between an abnormally seatedpassenger and a rear facing child seat, and the identification of avacant seat can be more reliably performed.

[0310] The outputs of the ultrasonic or electromagnetic sensors, theoutput of the weight sensor(s), the outputs of the seat positiondetecting sensor, and the outputs of the reclining angle detectingsensor are inputted to the neural network or other pattern recognitioncircuit, and the neural network determines the correlation function,based on training thereof during a training phase. The correlationfunction is then typically implemented in or incorporated into amicrocomputer. For the purposes herein, neural network will be used toinclude both a single neural network, a plurality of neural networks(including serial and parallel modular neural networks, ensemble neuralnetworks, vector support machines etc.), and other similar patternrecognition circuits or algorithms and combinations thereof.

[0311] For the ultrasonic implementation, to provide the input from theultrasonic sensors to the neural network (circuit), it is preferablethat an initial reflected wave portion and a last reflected wave portionare removed from each of the reflected waves of the ultrasonic sensorsand then the output data is processed. The neural network determines thecorrelation function by performing a weighting process, based on outputdata from the plurality of ultrasonic sensors, output data from theweight sensor(s), output data from the seat position detecting sensor ifpresent, and/or on output data from the reclining angle detecting sensorif present and any other relevant sensors.

[0312] With this arrangement, the portions of the reflected ultrasonicwave that do not contain useful information are removed from theanalysis and the presence and recognition of an object on the passengerseat can be more accurately performed. Similar data pruning can takeplace with electromagnetic sensors.

[0313] In a disclosed method for determining the occupancy of a seat ina passenger compartment of a vehicle in accordance with the invention,waves such as ultrasonic or electromagnetic waves are transmitted intothe passenger compartment toward the seat, reflected or modified wavesfrom the passenger compartment are received by a component which thengenerates an output representative thereof, the weight applied onto theseat is measured and an output is generated representative thereof andthen the seated-state of the seat is evaluated based on the outputs fromthe sensors and the weight measuring means.

[0314] The evaluation the seated-state of the seat may be accomplishedby generating a function correlating the outputs representative of thereceived waves and the measured weight and the seated-state of the seat,and incorporating the correlation function into a microcomputer. In thealternative, it is possible to generate a function correlating theoutputs representative of the received waves and the measured weight andthe seated-state of the seat in a neural network (circuit), and executethe function using the outputs representative of the received waves andthe measured weight as input into the neural network.

[0315] To enhance the seated-state determination, the position of a seatis measured and an output representative thereof is generated, and thenthe seated-state of the seat is evaluated based on the outputsrepresentative of the received reflected waves, the measured weight andthe measured seat position. In addition to or instead of measuring theseat position, it is possible to measure the reclining angle of theseat, i.e., the angle between the seat portion and the back portion ofthe seat, and generate an output representative thereof, and thenevaluate the seated-state of the seat based on the outputsrepresentative of the received waves, the measured weight and themeasured reclining angle of the seat (and seat position, if measured).

[0316] Furthermore, the output representative of the measured weight maybe compared with a reference value, and the occupying object of the seatidentified, e.g., as an adult or a child, based on the comparison of themeasured weight with the reference value.

[0317] In additional embodiments, the present invention involves themeasurement of one or more morphological characteristics of a vehicleoccupant and the use of these measurements to classify the occupant asto size and weight, and then to use this classification to position avehicle component, such as the seat, to a near optimum position for thatclass of occupant. Additional information concerning occupantpreferences can also be associated with the occupant class so that whena person belonging to that particular class occupies the vehicle, thepreferences associated with that class are implemented. Thesepreferences and associated component adjustments include the seatlocation after it has been manually adjusted away from the positionchosen initially by the system, the mirror location, temperature, radiostation, steering wheel and steering column positions, pedal positionsetc. The preferred morphological characteristics used are the occupantheight from the vehicle seat, weight of the occupant and facialfeatures. The height is determined by sensors, usually ultrasonic orelectromagnetic, located in the headrest, headliner or anotherconvenient location. The weight is determined by one of a variety oftechnologies that measure either pressure on or displacement of thevehicle seat or the force in the seat supporting structure. The facialfeatures are determined by image analysis comprising an imager such as aCCD or CMOS camera plus additional hardware and software.

[0318] The preferred system of measuring weight on the occupancy seat isdisclosed in co-pending U.S. patent application Ser. No. 09/193,209,filed Nov. 17, 1988, which is incorporated herein by reference. Thispatent application describes a weighing system based on the force orstrain imparted to the seat structure by the seat occupant. Preferably,the invention is implemented by placing strain gage sensors on the mainsupporting structures of the vehicle seat. An alternate approach, whichwill be described in more detail below, utilizes a bladder, which canhave one or more chambers, wherein at least one chamber has a pressuresensor capable of measuring the pressure of the fluid in the chamber.The chambers may be filled with air or other gas, liquid or a jell. Thechambers may be fluid connected or isolated. A single chamber issufficient if the overall weight of the occupant is desired. If theweight distribution of the occupant is required, then multiple chambersbecome necessary. If the bladder is properly designed, then the totalweight of the occupant can be determined by summing the forces on theindividual chambers (pressure×area). One example of the system will bedescribed in more detail below.

[0319] Accordingly, in order to achieve one or more of the objectsabove, a vehicle seat structure comprises a seat defining a surfaceadapted to contact an occupying item and a weight sensor arrangementarranged in connection with the seat for providing an indication of theweight applied by the occupying item to the surface of the seat. Theweight sensor arrangement includes conductive members spaced apart fromone another such that a capacitance develops between opposed ones ofconductive members upon incorporation of the conductive members in anelectrical circuit. The capacitance is based on the space between theconductive members which varies in relation to the weight applied by theoccupying item to the surface of the seat. The weight sensor arrangementmay include a pair of non-metallic substrates and a layer of materialsituated between the non-metallic substrates, possibly a compressiblematerial. The conductive members may comprise a first electrode arrangedon a first side of the material layer and a second electrode arranged ona second side of the material layer. The weight sensor arrangement maybe arranged in connection with slide mechanisms adapted to support theseat on a substrate of the vehicle while enabling movement of the seat,possibly between the slide mechanisms and the seat or between the floorand the slide mechanism. If bolts attach the seat to the slidemechanisms, the conductive members may be annular and placed on thebolts.

[0320] Another embodiment of a seat structure comprises a seat defininga surface adapted to contact an occupying item, slide mechanisms adaptedto support the seat on a substrate of the vehicle while enablingmovement of the seat and a weight sensor arrangement interposed betweenthe seat and the slide mechanisms for measuring displacement of the seatwhich provides an indication of the weight applied by the occupying itemto the seat. The weight sensor arrangement can include a capacitancesensor which measures a capacitance which varies in relation to thedisplacement of the seat. The capacitance sensor can include conductivemembers spaced apart from one another such that a capacitance developsbetween opposed ones of the conductive members upon incorporation of themembers in an electrical circuit, the capacitance being based on thespace between the members which varies in relation to the weight appliedby the occupying item to the seat.

[0321] The weight sensor arrangement can comprise a spring systemarranged underneath a seat cushion and a sensor arranged in associationwith the spring system for generating a signal based on downwardmovement of the cushion caused by occupancy of the seat which isindicative of the weight of the occupying item. The sensor may be adisplacement sensor structured and arranged to measure displacement ofthe spring system caused by occupancy of the seat. Such a sensor cancomprise a spring retained at both ends and which is tensioned upondownward movement of the spring system and measuring means for measuringa force in the spring indicative of weight of the occupying item. Themeasuring means can comprise a strain gage for measuring strain of thespring or a force-measuring device.

[0322] The sensor may also comprise a support, a cable retained at oneend by the support and a length-measuring device arranged at an oppositeend of the cable for measuring elongation of the cable indicative ofweight of the occupying item. The sensor can also comprises one or moreSAW strain gages and/or structured and arranged to measure a physicalstate of the spring system. If a bladder weight sensor is used, thepressure sensor can be a SAW based pressure sensor.

[0323] In one weight measuring method in accordance with the inventiondisclosed above, at least one strain gage transducer is mounted at arespective location on the support structure and provides a measurementof the strain of the support structure at that location, and the weightof the occupying item of the seat is determined based on the strain ofthe support structure measured by the strain gage transducer(s). Inanother method, the seat includes the slide mechanisms for mounting theseat to a substrate and bolts for mounting the seat to the slidemechanisms, the pressure exerted on the seat is measured by at least onepressure sensor arranged between one of the slide mechanisms and theseat. Each pressure sensor typically comprises first and second layersof shock absorbing material spaced from one another and a pressuresensitive material interposed between the first and second layers ofshock absorbing material. The weight of the occupying item of the seatis determined based on the pressure measured by the at least onepressure sensor. In still another method for measuring the weight of anoccupying item of a seat, a load cell is mounted between the seat and asubstrate on which the seat is supported. The load cell includes amember and a strain gage arranged thereon to measure tensile straintherein caused by weight of an occupying item of the seat. The weight ofthe occupying item of the seat is determined based on the strain in themember measured by the strain gage. Naturally, the load cell can beincorporated at other locations in the seat support structure and neednot be between the seat and substrate. In such a case, however, the seatwould need to be especially designed for that particular mountinglocation. The seat would then become the weight measuring device.

[0324] Furthermore, although the weight measuring system and apparatusdescribed above are described for particular use in a vehicle, it is ofcourse possible to apply the same constructions to measure the weight ofan occupying item on other seats in non-vehicular applications, if aweight measurement is desired for some purpose.

[0325] Thus, disclosed above are apparatus for measuring the weight ofan occupying item of a seat including at least one strain gagetransducer, each mounted at a respective location on a support structureof the seat and arranged to provide a measurement of the strain of thesupport structure thereat. A control system is coupled to the straingage transducer(s) for determining the weight of the occupying item ofthe seat based on the strain of the support structure measured by thestrain gage transducer(s). The support structure of the seat is mountedto a substrate such as a floor pan of a motor vehicle. Electricalconnection means such as wires connect the strain gage transducer(s) tothe control system. Each strain gage transducer may incorporate signalconditioning circuitry and an analog to digital converter such that themeasured strain is output as a digital signal. The positioning of thestrain gage transducer(s) depends in large part on the actualconstruction of the support structure of the seat. Thus, when thesupport structure comprises two elongate slide mechanisms adapted to bemounted on the substrate and support members for coupling the seat tothe slide mechanisms, several strain gage transducers may be used, eacharranged on a respective support member. If the support structurefurther includes a slide member, another strain gage transducer may bemounted thereon. Means for increasing the accuracy of the strain gagetransducers and/or concentrating the strain caused by occupancy of theseat are advantageous and include, for example, forming a support memberfrom first and second tubes having longitudinally opposed ends and athird tube overlying the opposed ends of the first and second tubes andconnected to the first and second tubes whereby a strain gage transduceris arranged on the third tube. Naturally, other structural shapes may beused in place of one or more of the tubes.

[0326] Another disclosed embodiment of an apparatus for measuring theweight of an occupying item of a seat includes slide mechanisms formounting the seat to a substrate and bolts for mounting the seat to theslide mechanisms, the apparatus comprises at least one pressure sensorarranged between one of the slide mechanisms and the seat, and/orbetween the slide mechanism and the floor pan, for measuring pressureexerted on the seat. Each pressure sensor may comprise first and secondlayers of shock absorbing material spaced from one another and apressure sensitive material interposed between the first and secondlayers of shock absorbing material. A control system is coupled to thepressure sensitive material for determining the weight of the occupyingitem of the seat based on the pressure measured by the at least onepressure sensor. The pressure sensitive material may include anelectrode on upper and lower faces thereof.

[0327] Another disclosed embodiment of an apparatus for measuring theweight of an occupying item of a seat includes a load cell adapted to bemounted to the seat and to a substrate on which the seat is supported.The load cell includes a member and a strain gage arranged thereon tomeasure tensile strain in the member caused by weight of an occupyingitem of the seat. A control system is coupled to the strain gage fordetermining the weight of an occupying item of the seat based on thestrain in the member measured by the strain gage. If the member is abeam and the strain gage includes two strain sensing elements, then onestrain-sensing element is arranged in a longitudinal direction of thebeam and the other is arranged in a transverse direction of the beam. Iffour strain sensing elements are present, a first pair is arranged in alongitudinal direction of the beam and a second pair is arranged in atransverse direction of the beam. The member may be a tube in whichcase, a strain-sensing element is arranged on the tube to measurecompressive strain in the tube and another strain sensing element isarranged on the tube to measure tensile strain in the tube. The membermay also be an elongate torsion bar mounted at its ends to thesubstrate. In this case, the load cell includes a lever arranged betweenthe ends of the torsion bar and connected to the seat such that a torqueis imparted to the torsion bar upon weight being exerted on the seat.The strain gage thus includes a torsional strain-sensing element.

[0328] Furthermore, disclosed herein is, a vehicle seat comprises acushion defining a surface adapted to support an occupying item, aspring system arranged underneath the cushion and a sensor arranged inassociation with the spring system for generating a signal based ondownward movement of the cushion and/or spring system caused byoccupancy of the seat which is indicative of the weight of the occupyingitem. The spring system may be in contact with the sensor. The sensormay be a displacement sensor structured and arranged to measuredisplacement of the spring system caused by occupancy of the seat. Inthe alternative, the sensor may be designed to measure deflection of abottom of the cushion, e.g., placed on the bottom of the cushion.Instead of a displacement sensor, the sensor can comprise a springretained at both ends and which is tensioned upon downward movement ofthe spring system and measuring means for measuring a force in thespring indicative of weight of the occupying item. Non-limitingconstructions of the measuring means include a strain gage for measuringstrain of the spring or measuring means comprise a force measuringdevice. The sensor can also comprises a support, a cable retained at oneend by the support and a length-measuring device arranged at an oppositeend of the cable for measuring elongation of the cable indicative ofweight of the occupying item. In this case, the length measuring devicemay comprises a cylinder, a rod arranged in the cylinder and connectedto the opposite end of the cable, a spring arranged in the cylinder andconnected to the rod to resist elongation of the cable and windingsarranged in the cylinder. The amount of coupling between the windingsprovides an indication of the extent of elongation of the cable. Astrain gage can also be used to measure the change in length of thecable. In one particular embodiment, the sensor comprises one or morestrain gages structured and arranged to measure a physical state of thespring system or the seat. Electrical connection means such as wiresconnect the strain gage(s) to the control system. Each strain gagetransducer may incorporate signal conditioning circuitry and an analogto digital converter such that the measured strain is output as adigital signal. Alternately, a surface acoustical wave (SAW) strain gagecan be used in place of conventional wire, foil or silicon strain gagesand the strain measured either wirelessly or by a wire connection. ForSAW strain gages, the electronic signal conditioning can be associateddirectly with the gage or remotely in an electronic control module asdesired.

[0329] In a method for measuring weight of an occupying item on a seatcushion of a vehicle, a spring system is arranged underneath the cushionand a sensor is arranged in association with the cushion for generatinga signal based on downward movement of the cushion and/or spring systemcaused by the occupying item which is indicative of the weight of theoccupying item. The particular constructions of the spring system andsensor discussed above can be implemented in the method.

[0330] Another embodiment of a weight sensor system comprises a springsystem adapted to be arranged underneath the cushion and extend betweenthe supports and a sensor arranged in association with the spring systemfor generating a signal indicative of the weight applied to the cushionbased on downward movement of the cushion and/or spring system caused bythe weight applied to the seat. The particular constructions of thespring system and sensor discussed above can be implemented in thisembodiment.

[0331] An embodiment of a vehicle including an arrangement forcontrolling a component based on an occupying item of the vehiclecomprises a cushion defining a surface adapted to support the occupyingitem, a spring system arranged underneath the cushion, a sensor arrangedin association with the spring system for generating a signal indicativeof the weight of the occupying item based on downward movement of thecushion and/or spring system caused by occupancy of the seat and aprocessor coupled to the sensor for receiving the signal indicative ofthe weight of the occupying item and generating a control signal forcontrolling the component. The particular constructions of the springsystem and sensor discussed above can be implemented in this embodiment.The component may be an airbag module or several airbag modules, or anyother type of occupant protection or restraint device.

[0332] A method for controlling a component in a vehicle based on anoccupying item comprises the steps of arranging a spring system arrangedunderneath a cushion on which the occupying item may rest, arranging asensor in association with the cushion for generating a signal based ondownward movement of the cushion and/or spring system caused by theoccupying item which is indicative of the weight of the occupying item,and controlling the component based on the signal indicative of theweight of the occupying item. The particular constructions of the springsystem and sensor discussed above can be implemented in this method.

[0333] Further, disclosed above is a vehicle seat structure whichcomprises a seat or cushion defining a surface adapted to contact anoccupying item, slide mechanisms coupled to the seat for enablingmovement of the seat, support members for supporting the seat on theslide mechanisms such that at least a portion of the weight of theoccupying item passes through the support members. At least one of thesupport members has a region with a lower stiffness than a remainingregion of the support member. The remaining regions of the supportmember are not necessarily the entire remaining portions of the supportmember and they may be multiple regions with a lower stiffness thanother regions. A strain gage measurement system generates a signalindicative of the weight of the occupying item. The strain gagemeasurement system includes at least one strain gage transducer arrangedin a lower stiffness region of the support member to measure strainthereof. The support member(s) may be tubular whereby the lowerstiffness region has a smaller diameter than a diameter of the remainingregion. If the support member is not tubular, the lower stiffness regionmay have a smaller circumference than a circumference of a remainingregion of the support member. Each support member may have a first endconnected to one of the slide mechanisms and a second end connected tothe seat. Electrical connection means, such as wires or electromagneticwaves which transfer power wirelessly, connect the strain gagetransducer(s) to the control system. Each strain gage transducer mayincorporate signal conditioning circuitry and an analog to digitalconverter such that the measured strain is output as a digital signal.Alternately, a surface acoustical wave (SAW) strain gage can be used inplace of conventional wire, foil or silicon strain gages and the straintransmitted either wirelessly or by a wire connection. For SAW straingages, the electronic signal conditioning can be associated directlywith the gage or remotely in an electronic control module as desired.The strain gage measurement system preferably includes at least oneadditional strain gage transducer arranged on another support member anda control system coupled to the strain gage transducers for receivingthe strain measured by the strain gage transducers and providing thesignal indicative of the weight of the occupying item.

[0334] In a method for measuring weight of an occupying item in avehicle seat disclosed above, support members are interposed between theseat and slide mechanisms which enable movement of the seat and suchthat at least a portion of the weight of the occupying item passesthrough the support members, at least one of the support members isprovided with a region having a lower stiffness than a remaining region,at least one strain gage transducer is arranged in the lower stiffnessregion of the support member to measure strain thereof and an indicationof the weight of the occupying item is obtained based at least in parton the strain of the lower stiffness region of the support membermeasured by the strain gage transducer(s). The support member(s) may beformed by providing an elongate member and cutting around thecircumference of the elongate member to thereby obtain the lowerstiffness region or by other means.

[0335] A vehicular arrangement for controlling a component based on anoccupying item of the vehicle disclosed herein comprises a seat defininga surface adapted to contact the occupying item, slide mechanismscoupled to the seat for enabling movement of the seat, support membersfor supporting the seat on the slide mechanisms such that at least aportion of the weight of the occupying item passes through the supportmembers. At least one of the support members has a region with a lowerstiffness than a remaining region of the support member. A strain gagemeasurement system generates a signal indicative of the weight of theoccupying item, and a processor coupled to the strain gage measurementsystem receives the signal indicative of the weight of the occupyingitem and generates a control signal for controlling the component. Thestrain gage measurement system includes at least one strain gagetransducer arranged in the lower stiffness region of the support memberto measure strain thereof. The component can be any vehicular component,system or subsystem which can utilize the weight of the occupying itemof the seat for control, e.g., an airbag system.

[0336] Another method for controlling a component in a vehicle based onan occupying item disclosed herein comprises the steps of interposingsupport members between a seat on which the occupying item may rest andslide mechanisms which enable movement of the seat and such that atleast a portion of the weight of the occupying item passes through thesupport members, providing at least one of the support members with aregion having a lower stiffness than a remaining region, arranging atleast one strain gage transducer in the lower stiffness region of thesupport member to measure strain thereof, and controlling the componentbased at least in part on the strain of the lower stiffness region ofthe support member measured by the strain gage transducer(s). If thecomponent is an airbag, the step of controlling the component can entailcontrolling the rate of deployment of the airbag, the start time ofdeployment, the inflation rate of the airbag, the rate of gas removalfrom the airbag and/or the maximum pressure in the airbag. In anotherweight measuring system, one or more of the connecting members whichconnect the seat to the slide mechanisms comprises an elongate studhaving first and second threaded end regions and an unthreadedintermediate region between the first and second threaded end regions,the first threaded end region engaging the seat and the second threadedend region engaging one of the slide mechanisms, and a strain gagemeasurement system arranged on the unthreaded intermediate region formeasuring strain in the connecting member at the unthreaded intermediateregion which is indicative of weight being applied by an occupying itemin the seat. The strain gage measurement system may comprises a SAWstrain gage and associated circuitry and electric components capable ofreceiving a wave and transmitting a wave modified by virtue of thestrain in the connecting member, e.g., an antenna. The connecting membercan be made of a non-metallic, composite material to avoid problems withthe electromagnetic wave propagation. An interrogator may be providedfor communicating wirelessly with the SAW strain gage measurementsystem.

[0337] The weight measuring apparatus described above may be used inapparatus and methods for adjusting a vehicle component, although otherweight measuring apparatus may also be used in the vehicle componentadjusting systems and methods described immediately below.

[0338] One embodiment of such an apparatus in accordance with inventionincludes a first measuring system for measuring a first morphologicalcharacteristic of the occupying item of the seat and a second measuringsystem for measuring a second morphological characteristic of theoccupying item. Morphological characteristics include the weight of theoccupying item, the height of the occupying item from the bottom portionof the seat and if the occupying item is a human, the arm length, headdiameter, facial features and leg length. The apparatus also includesprocessor means for receiving the output of the first and secondmeasuring systems and for processing the outputs to evaluate aseated-state based on the outputs. The measuring systems describedherein, as well as any other conventional measuring systems, may be usedin the invention to measure the morphological characteristics of theoccupying item.

[0339] One preferred embodiment of an adjustment system in accordancewith the invention includes a plurality of wave-receiving sensors forreceiving waves from the seat and its contents, if any, and one or moreweight sensors for detecting weight of an occupant in the seat or anabsence of weight applied onto the seat indicative of a vacant seat. Theweight sensing apparatus may include strain sensors mounted on orassociated with the seat structure such that the strain measuringelements respond to the magnitude of the weight of the occupying item.The apparatus also includes processor means for receiving the output ofthe wave-receiving sensors and the weight sensor(s) and for processingthe outputs to evaluate a seated-state based on the outputs. Theprocessor means then adjusts a part of the component or the component inits entirety based at least on the evaluation of the seated-state of theseat. The wave-receiving sensors may be ultrasonic sensors, opticalsensors or electromagnetic sensors. If the wave-receiving sensors areultrasonic or optical sensors, then they may also include transmittermeans for transmitting ultrasonic or optical waves toward the seat. Ifthe component is a seat, the system includes power means for moving atleast one portion of the seat relative to the passenger compartment andcontrol means connected to the power means for controlling the powermeans to move the portion(s) of the seat. In this case, the processormeans may direct the control means to affect the power means based atleast in part on the evaluation of the seated-state of the seat. Withrespect to the direction or regulation of the control means by theprocessor means, this may take the form of a regulation signal to thecontrol means that no seat adjustment is needed, e.g., if the seat isoccupied by a bag of groceries or a child seat in a rear orforward-facing position as determined by the evaluation of the outputfrom the ultrasonic or optical and weight sensors. On the other hand, ifthe processor means determines that the seat is occupied by an adult orchild for which adjustment of the seat is beneficial or desired, thenthe processor means may direct the control means to affect the powermeans accordingly. For example, if a child is detected on the seat, theprocessor means may be designed to lower the headrest. In certainembodiments, the apparatus may include one or more sensors each of whichmeasures a morphological characteristic of the occupying item of theseat, e.g., the height or weight of the occupying item, and theprocessor means are arranged to obtain the input from these sensors andadjust the component accordingly. Thus, once the processor meansevaluates the occupancy of the seat and determines that the occupancy isby an adult or child, then the processor means may additionally useeither the obtained weight measurement or conduct additionalmeasurements of morphological characteristics of the adult or childoccupant and adjust the component accordingly. The processor means maybe a single microprocessor for performing all of the functions describedabove. In the alternative, one microprocessor may be used for evaluatingthe occupancy of the seat and another for adjusting the component. Theprocessor means may comprise an evaluation circuit implemented inhardware as an electronic circuit or in software as a computer program.In certain embodiments, a correlation function or state between theoutput of the various sensors and the desired result (i.e., seatoccupancy identification and categorization) is determined, e.g., by aneural network that may be implemented in hardware as a neural computeror in software as a computer program. The correlation function or statethat is determined by employing this neural network may also becontained in a microcomputer. In this case, the microcomputer can beemployed as an evaluation circuit. The word circuit herein will be usedto mean both an electronic circuit and the functional equivalentimplemented on a microcomputer using software. In enhanced embodiments,a heartbeat sensor may be provided for detecting the heartbeat of theoccupant and generating an output representative thereof. The processormeans additionally receive this output and evaluate the seated-state ofthe seat based in part thereon. In addition to or instead of such aheartbeat sensor, a capacitive or electric field sensor and/or a motionsensor may be provided. The capacitive or electric field sensor detectsthe presence of the occupant and generates an output representative ofthe presence of the occupant. The motion sensor detects movement of theoccupant and generates an output representative thereof. These outputsare provided to the processor means for possible use in the evaluationof the seated-state of the seat.

[0340] The portion of the apparatus which includes the ultrasonic,optical or electromagnetic sensors, weight measuring means and processormeans which evaluate the occupancy of the seat based on the measuredweight of the seat and its contents and the returned waves from theultrasonic, optical or electromagnetic sensors may be considered toconstitute a seated-state detecting unit. The seated-state detectingunit may further comprise a seat track position-detecting sensor. Thissensor determines the position of the seat on the seat track in theforward and aft direction. In this case, the evaluation circuitevaluates the seated-state, based on a correlation function obtainedfrom outputs of the ultrasonic sensors, an output of the one or moreweight sensors, and an output of the seat track position detectingsensor. With this structure, there is the advantage that theidentification between the flat configuration of a detected surface in astate where a passenger is not sitting in the seat and the flatconfiguration of a detected surface which is detected when a seat isslid backwards by the amount of the thickness of a passenger, that is,of identification of whether a passenger seat is vacant or occupied by apassenger, can be reliably performed. Furthermore, the seated-statedetecting unit may also comprise a reclining angle detecting sensor, andthe evaluation circuit may also evaluate the seated-state based on acorrelation function obtained from outputs of the ultrasonic, optical orelectromagnetic sensors, an output of the weight sensor(s), and anoutput of the reclining angle detecting sensor. In this case, if thetilted angle information of the back portion of the seat is added asevaluation information for the seated-state, identification can beclearly performed between the flat configuration of a surface detectedwhen a passenger is in a slightly slouching state and the configurationof a surface detected when the back portion of a seat is slightly tiltedforward and similar difficult-to-discriminate cases.

[0341] This embodiment may even be combined with the output from a seattrack position-detecting sensor to further enhance the evaluationcircuit. Moreover, the seated-state detecting unit may further comprisea comparison circuit for comparing the output of the weight sensor(s)with a reference value. In this case, the evaluation circuit identifiesan adult and a child based on the reference value. Preferably, theseated-state detecting unit comprises: a plurality of ultrasonic,optical or electromagnetic sensors for transmitting ultrasonic orelectromagnetic waves toward a seat and receiving reflected waves fromthe seat; one or more weight sensors for detecting weight of a passengerin the seat; a seat track position detecting sensor; a reclining angledetecting sensor; and a neural network circuit to which outputs of theultrasonic or electromagnetic sensors and the weight sensor(s), anoutput of the seat track position detecting sensor, and an output of thereclining angle detecting sensor are inputted and which evaluatesseveral kinds of seated-states, based on a correlation function obtainedfrom the outputs. The kinds of seated-states that can be evaluated andcategorized by the neural network include the following categories,among others, (i) a normally seated passenger and a forward facing childseat, (ii) an abnormally seated passenger and a rear-facing child seat,and (iii) a vacant seat. The seated-state detecting unit may furthercomprise a comparison circuit for comparing the output of the weightsensor(s) with a reference value and a gate circuit to which theevaluation signal and a comparison signal from the comparison circuitare input. This gate circuit, which may be implemented in software orhardware, outputs signals which evaluates several kinds ofseated-states. These kinds of seated-states can include a (i) normallyseated passenger, (ii) a forward facing child seat, (iii) an abnormallyseated passenger, (iv) a rear facing child seat, and (v) a vacant seat.With this arrangement, the identification between a normally seatedpassenger and a forward facing child seat, the identification between anabnormally seated passenger and a rear facing child seat, and theidentification of a vacant seat can be more reliably performed. Theoutputs of the plurality of ultrasonic or electromagnetic sensors, theoutput of the weight sensor(s), the outputs of the seat track positiondetecting sensor, and the outputs of the reclining angle detectingsensor are inputted to the neural network or other pattern recognitioncircuit, and the neural network circuit determines the correlationfunction, based on training thereof during a training phase. Thecorrelation function is then typically implemented in or incorporatedinto a microcomputer. For the purposes herein, neural network will beused to include both a single neural network, a plurality of neuralnetworks, and other similar pattern recognition circuits or algorithmsand combinations thereof including the combination of neural networksand fuzzy logic systems such as neural-fuzzy systems. To provide theinput from the ultrasonic or electromagnetic sensors to the neuralnetwork circuit, it is preferable that an initial reflected wave portionand a last reflected wave portion are removed from each of the reflectedwaves of the ultrasonic or electromagnetic sensors and then the outputdata is processed. This is a form of range gating. With thisarrangement, the portions of the reflected ultrasonic or electromagneticwave that do not contain useful information are removed from theanalysis and the presence and recognition of an object on the passengerseat can be more accurately performed. The neural network circuitdetermines the correlation function by performing a weighting process,based on output data from the plurality of ultrasonic or electromagneticsensors, output data from the weight sensor(s), output data from theseat track position detecting sensor if present, and/or on output datafrom the reclining angle detecting sensor if present. Additionally, inadvanced systems, outputs from the heartbeat and occupant motion sensorsmay be included.

[0342] In a disclosed method for determining the occupancy of a seat ina passenger compartment of a vehicle in accordance with the invention,waves such as ultrasonic or electromagnetic waves are transmitted intothe passenger compartment toward the seat, reflected waves from thepassenger compartment are received by a component which then generatesan output representative thereof, the weight applied onto the seat ismeasured and an output is generated representative thereof and then theseated-state of the seat is evaluated based on the outputs from thesensors and the weight measuring means. The evaluation the seated-stateof the seat may be accomplished by generating a function correlating theoutputs representative of the received reflected waves and the measuredweight and the seated-state of the seat, and incorporating thecorrelation function into a microcomputer. In the alternative, it ispossible to generate a function correlating the outputs representativeof the received reflected waves and the measured weight and theseated-state of the seat in a neural network circuit, and execute thefunction using the outputs representative of the received reflectedwaves and the measured weight as input into the neural network circuit.To enhance the seated-state determination, the position of a seat trackof the seat is measured and an output representative thereof isgenerated, and then the seated-state of the seat is evaluated based onthe outputs representative of the received reflected waves, the measuredweight and the measured seat track position. In addition to or insteadof measuring the seat track position, it is possible to measure thereclining angle of the seat, i.e., the angle between the seat portionand the back portion of the seat, and generate an output representativethereof, and then evaluate the seated-state of the seat based on theoutputs representative of the received reflected waves, the measuredweight and the measured reclining angle of the seat (and seat trackposition, if measured). Furthermore, the output representative of themeasured weight may be compared with a reference value, and theoccupying object of the seat identified, e.g., as an adult or a child,based on the comparison of the measured weight with the reference value.

[0343] In additional embodiments, the present invention involves themeasurement of one or more morphological characteristics of a vehicleoccupant and the use of these measurements to classify the occupant asto size and weight, and then to use this classification to position avehicle component, such as the seat, to a near optimum position for thatclass of occupant. Additional information concerning occupantpreferences can also be associated with the occupant class so that whena person belonging to that particular class occupies the vehicle, thepreferences associated with that class are implemented. Thesepreferences and associated component adjustments include the seatlocation after it has been manually adjusted away from the positionchosen initially by the system, the mirror location, temperature, radiostation, visor, steering wheel and steering column positions, etc. Thepreferred morphological characteristics used are the occupant heightfrom the vehicle seat and weight of the occupant. The height isdetermined by sensors, usually ultrasonic or electromagnetic, located inthe headrest or another convenient location. The weight is determined byone of a variety of technologies that measure either pressure on ordisplacement of the vehicle seat or the force or strain in the seatsupporting structure.

[0344] Although several preferred embodiments are illustrated anddescribed above, there are possible combinations using other geometries,sensors, materials and different dimensions for the components thatperform the same functions. This invention is not limited to the aboveembodiments and should be determined by the following claims. Forexample, the weight measuring apparatus and methods described abovecould be used in conjunction with a seat position sensor to provide foran accurate determination of the identification and location of theoccupying item of the seat.

What is claimed is:
 1. An arrangement for determining weight of anoccupying item in a seat, comprising: at least one weight sensorarranged to obtain a measurement of the force applied to the seat; aforcing function determination arrangement for measuring a forcingfunction of the seat; and a processor coupled to said at least oneweight sensor and said forcing function determination arrangement forreceiving the measurement of the force applied to the seat from said atleast one weight sensor and the measurement of the forcing function fromsaid forcing function measurement system and determining the weight ofthe occupying item based thereon.
 2. The arrangement of claim 1, whereinsaid forcing function determination arrangement comprises at least oneaccelerometer.
 3. The arrangement of claim 2, wherein said at least oneaccelerometer includes a vertical accelerometer.
 4. The arrangement ofclaim 1, wherein said at least one weight sensor comprises a bladderhaving at least one chamber and at least one transducer for measuringthe pressure in a respective one of said at least one chamber.
 5. Thearrangement of claim 1, wherein said forcing function determinationarrangement is arranged to measure effects on the seat caused by load ofa seatbelt associated with the seat whereby the forcing function isdependent on the load caused by the seatbelt.
 6. The arrangement ofclaim 1, wherein said forcing function determination arrangement isarranged to measure effects on the seat of road roughness, steeringmaneuvers, and a vehicle suspension system whereby the forcing functionis dependent on the road roughness, steering maneuvers and the vehiclesuspension system.
 7. The arrangement of claim 1, wherein said processoris arranged to determine whether the occupying item is belted byanalyzing the measurements from by said at least one weight sensor overtime and the forcing function of the seat from said forcing functiondetermination arrangement over time.
 8. The arrangement of claim 1,wherein said processor is arranged to differentiate between animate andinanimate objects by analyzing measurements from said at least oneweight sensor over time and the forcing function of the seat from saidforcing function determination arrangement over time.
 9. The arrangementof claim 1, wherein said processor is arranged to determine the positionof the occupying item on the seat by analyzing the measurements fromsaid at least one weight sensor over time and the forcing function ofthe seat from said forcing function determination arrangement over time.10. An arrangement for determining weight of an occupying item in aseat, comprising: at least one weight sensor arranged to obtain ameasurement of the force applied to the seat by the occupying item;measuring means for measuring dynamic forces being applied to the seat;and a processor coupled to said at least one weight sensor and saidmeasuring means for receiving the measurement of the force applied tothe seat from said at least one weight sensor and the dynamic forcesfrom said measuring means and determining the weight of the occupyingitem based thereon.
 11. The arrangement of claim 10, wherein saidmeasuring means comprises at least one accelerometer.
 12. Thearrangement of claim 11, wherein said at least one accelerometerincludes a vertical accelerometer.
 13. The arrangement of claim 10,wherein said at least one weight sensor comprises a bladder having atleast one chamber and at least one transducer for measuring the pressurein a respective one of said at least one chamber.
 14. The arrangement ofclaim 10, wherein said measuring means are arranged to measure effectson the seat caused by load of a seatbelt associated with the seat. 15.The arrangement of claim 10, wherein said measuring means are arrangedto measure effects on the seat of road roughness, steering maneuvers,and a vehicle suspension system.
 16. The arrangement of claim 10,wherein said processor is arranged to determine whether the occupyingitem is belted by analyzing the measurements from by said at least oneweight sensor over time and the dynamic forces applied to the seat fromsaid measuring means over time.
 17. The arrangement of claim 10, whereinsaid processor is arranged to differentiate between animate andinanimate objects by analyzing measurements from said at least oneweight sensor over time and the dynamic forces applied to the seat fromsaid measuring means over time.
 18. The arrangement of claim 10, whereinsaid processor is arranged to determine the position of the occupyingitem on the seat by analyzing the measurements from said at least oneweight sensor over time and the dynamic forces applied to the seat fromsaid measuring means over time.
 19. An arrangement for classifying anoccupying item in a seat, comprising: at least one weight sensorarranged to measure the force applied to the seat at time intervals; anda processor coupled to said at least one weight sensor for receiving theforce measurements from said at least one weight sensor, said processorbeing arranged to analyze the force measurements from said at least oneweight sensor over time to discern patterns providing classificationinformation about the occupying item.
 20. The arrangement of claim 19,wherein said processor is trained to discern patterns providinginformation about the occupying item by conducting tests in whichdifferent occupying items are placed in the seat and measurements of theforce applied to the seat are obtained by said at least one weightsensor, before, during and after placement of the occupying item in theseat.
 21. The arrangement of claim 19, further comprising a forcingfunction determination arrangement coupled to said processor formeasuring a forcing function of the seat, said processor being arrangedto consider the forcing function in the discerning of the patternsproviding classification information about the occupying item.
 22. Thearrangement of claim 19, further comprising measuring means coupled tosaid processor for measuring dynamic forces applied to the seat, saidprocessor being arranged to consider the dynamic forces applied to theseat in the discerning of the patterns providing classificationinformation about the occupying item.
 23. A method for determiningweight of an occupying item in a seat of a vehicle, comprising the stepsof: measuring the force applied to the seat; measuring a forcingfunction of the seat; and determining the weight of the occupying itembased on the measured force applied to the seat and the measured forcingfunction.
 24. The method of claim 23, wherein the step of measuring theforcing function comprises the step of arranging at least oneaccelerometer on the vehicle.
 25. The method of claim 24, wherein the atleast one accelerometer includes a vertical accelerometer.
 26. Themethod of claim 23, wherein the step of measuring the force applied tothe seat comprises the steps of arranging a bladder having at least onechamber in the seat and measuring the pressure in the at least onechamber by means of a respective transducer.
 27. The method of claim 23,wherein the step of measuring the forcing function comprises the step ofderiving the forcing function based in part on the effects on the seatcaused by load of a seatbelt associated with the seat.
 28. The method ofclaim 23, wherein the step of measuring the forcing function comprisesthe step of deriving the forcing function based in part on the effectson the seat of road roughness, steering maneuvers, and a vehiclesuspension system.
 29. A method for determining weight of an occupyingitem in a seat, comprising the steps of: measuring the force applied tothe seat; measuring dynamic forces applied to the seat; and determiningthe weight of the occupying item based on the measured force applied tothe seat and the measured dynamic forces applied to the seat.
 30. Themethod of claim 29, wherein the step of measuring the forcing functioncomprises the step of arranging at least one accelerometer on thevehicle.
 31. The method of claim 30, wherein the at least oneaccelerometer includes a vertical accelerometer.
 32. The method of claim29, wherein the step of measuring the force applied to the seatcomprises the steps of arranging a bladder having at least one chamberin the seat and measuring the pressure in the at least one chamber bymeans of a respective transducer.
 33. A method for classifying anoccupying item in a seat, comprising the steps of: measuring the forceapplied to the seat at time intervals; and identifying patternsindicative of a classification of particular occupying items based onthe measurements of the force applied to the seat over time.
 34. Themethod of claim 33, wherein the step of identifying patterns comprisesthe step of utilizing a pattern recognition algorithm to identifypatterns from the measurements of the force applied to the seat overtime.
 35. The method of claim 34, wherein the step of identifyingpatterns further comprises the step of training the pattern recognitionalgorithm by conducting tests in which different occupying items areplaced in the seat and measuring the force applied to the seat before,during and after placement of the occupying item in the seat.
 36. Themethod of claim 33, further comprising the step of measuring a forcingfunction of the seat, the step of identifying patterns furthercomprising the step of identifying patterns based on the measurements ofthe force applied to the seat and the forcing function.
 37. The methodof claim 33, further comprising the step of measuring dynamic forcesapplied to the seat, the step of identifying patterns further comprisingthe step of identifying patterns based on the measurements of the forceapplied to the seat and the measurements of the dynamic forces appliedto the seat.